. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . The International Linear Collider: A Detector Physicist Describes Accelerator Physics to String Theorists . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .
Download ReportTranscript . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . The International Linear Collider: A Detector Physicist Describes Accelerator Physics to String Theorists . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . The International Linear Collider: A Detector Physicist Describes Accelerator Physics to String Theorists . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . George Gollin Department of Physics University of Illinois at Urbana-Champaign . . .. . . . . . . .. . 1 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . .. . . . . . . . .. . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Doing something different . . .. . . . . . . .. . 2 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . .. . . . (mixed-signal . • engineering electronics and mechanical devices) . . . . . . . • software (large .analysis codes) • theory/phenomenology (results from quantum field theory) . . . . . . . . . . . I have been concentrating on ILC accelerator physics since mid2002. The tools are different: • engineering (power RF and acoustics) • software (small modeling codes and test beam data analyses) • theory/phenomenology (classical mechanics, electrodynamics) . . .. . . . . . . .. . 3 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . I am really. a .detector physicist. My usual tool. set: . . . . . . . Classical physics as a research tool .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The work is. well-suited to undergraduate participation. In . . . . . . . . . . . . . particular, small codes and classical physics permit inexperienced . . . . . . . . . . students to work productively after only a few weeks. . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . Doing something different . So far: • eight undergraduates, working on two separate projects • one senior thesis, with a second in the pipeline The students participate in planning, managing our Fermilab test beam running, and developing models for systems we study. It is a great deal of fun, but now we need serious support. . . .. . . . . . . .. . 4 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We. .have been (we were the first) for a small ILC . proponents . . . . .. . damping ring. . . . . . . . . . . . . . The original damping ring design had a circumference of 17 km. The UIUC/Fermilab/Argonne design has a circumference of 6 km. The baseline design report specifies 6.6 km damping rings. !!! . . .. . . . . . . .. . 5 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . We have an impact . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . . . . .. . . . . . . .. . 6 .. George Gollin, The International Linear Collider . . . . . . . . . . . . . . A linear collider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I . . .. . . .. . Physics P llinois . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . A highly simplified view of an e+e- linear collider . . . . . . . . . . . . . . . . preaccelerator . . 5. GeV . . . . . . . . . . . . . . . . . . e± source . . . . . . . . . . . . . . . . . . . . . 120 keV. . . .. . . .. . detector . . damping ring 250 - 500 GeV dump . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . 5 GeV main linac bunch compressor final collimation focus The ILC accelerator complex will be incredibly complicated. . . .. . . . . . . .. . 7 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . The ILC will be filled with cool stuff, interesting devices, and . . . . . marvelous gizmos. . . . . . Many of them are easily described using classical mechanics and classical electrodynamics. For fun, here are some of the issues and devices that have interested me. . . .. . . . . . . .. . 8 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . Really cool stuff . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . What do we mean when we say E E and E E ? . . .. . . . . . . .. . 9 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . Fields of a charge in uniform motion . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . Sensors are 1. . meter from the origin in their rest frames. The moving .. . . . . . . . . . . . . frame carries a charge Q fixed to its .origin.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . As sensors B and B align, they measure the electric. fields EB and EB . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. .. . . . Two observers prepare to measure E . . As sensors A and A align, they measure the electric fields EA and EA B B B B EB = EB B B EA = EA Q Q .... . .. . . . . .. . . . . . . . . .. . . . . 10 .. . George Gollin, The International Linear Collider .. . I Physics P llinois A A A . Q A A . . A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A . . . . . . . . . . . A . . . . . . . . .. . . . . .. . B . . . EA = EA A A A Q . . . B . . . . . . Q The measurement EA = EA is made when Q is 1/ meters from sensor A in the unprimed (stationary) frame. When Q is 1 meter from sensor A, the sensor will measure a field that is weaker by a factor of 1/ 2. . . .. . . . . . . .. . 11 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . = EB . . . .. . . . . . . . . EB B . . . . . . . . .. . . B . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . Q . . . A . . . Two observers prepare to measure E .. B . . . B. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 32 . . . . . as 0 1 2 E sin 2 32 1; q 4 0 r ~ as 90 2 1 23 . .... . .. . . . . .. . . . . . . . . when 2 q George Gollin, The International Linear Collider 12 . . . . 2 . . . . q 4 0 r Physics P llinois . . . I 4 0 r 2 1 2 sin 2 E E . . . . 1 2 2 . . . . q E . . 1 . .. . E . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . frame in .which . is in motion . The electric field in the q is seen to be .. . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . .. . . . E ~ 1/2 and E ~ . . . . . . . . . . . . . . . . . . .. Fields of a relativistic charge in uniform motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . Field lines,. . schematically: . . . . . . . . . . . .. .. . . . . . . . . Note that the total number of field lines is the same in both cases. . . .. . . . . . . .. . 13 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . ILC bunches . . .. . . . . . . .. . 14 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . sz 300 mm . . . . . . . . 5.7 nm . . . . sy . . . . . sx nC) . . 655 nm (3.2 . . . . e±. . . x z . . . . . . 15 .. . . . . . . . . . . . . George Gollin, The International Linear Collider .... . .. . . . . .. . . . . . .. . . y top view: beam traveling to the right .. . . . . . x . . . . . . . beam coming out of the page . . . . . . . . . . 21010 . . .. y z I . 250 GeV . . . number of bunches 2820 A bunch is 115 times wider than it is thick… Physics P llinois . . . . . …and 458 times longer than it is wide. . .. . bunch charge .. . . . . . . . . . bunch energy . . . . . . . . . . . . Bunch parameters continue. .to . . . evolve. Here’s a .typical .set.. . .. . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . .. . . . ILC bunch parameters . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . rest frame . . Bunch is highly relativistic. (In its it is ~147 m long!) . . .. . . . . . . . . . . B . . . . . . .. . . . . . . . . . . E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. Fields near an ILC bunch . . eB E The fields just above/below the bunch are large in the lab frame: E ~ 1.5 1011 V/m = 150 V/nm B ~ 500 T Energy density in the fields is appreciable: u ~ 1 keV/nm3 . . .. . . . . . . .. . 16 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . collide. .. . . . and compresses the bunches as they v B force. is. . appreciable .. . . . . . . . . . . . . . . . . .. . . B B . y . . . . . . . . . . .................. .............. .......... ....... ................................................................... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B . . . . . . . . . . . . B . e- . . . . . . . . . . ........................................................... ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....................................................... ......... ........................ . B . . . . . . . . . . . . . . . . . . . . . . . B e+ B Inside a bunch the focusing force increases with (vertical) distance from the horizontal median plane of the bunches since B increases The effect is significant: a naïve estimate shows an e± will oscillate through the median plane a few times while the bunches cross. . . .. . . . . . . .. . 17 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . .. .. . . . . . . . Bunches focus each other during collision . . . . . . . . . . . . . . . . . . . . Particles oscillate around the horizontal median plane . . . . . . . . . . . . . . . . . . . .. . . .. . . . .. . . 18 .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . From Nick Walker’s USPAS Santa Barbara (2003) material: http://www.desy.de/~njwalker/uspas/coursemat/pp/unit_7.ppt George Gollin, The International Linear Collider . . . . . . . . . . . . . . . . . . . . . . . . .. . . I . .. . . .. . Physics P llinois . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bunch geometry here isn’t quite the same as current ILC specs . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . http://www.slac.stanford.edu/~seryi/LCD_May28_2002/web/zxy.gif play the animation… . . .. . . . . . . .. . 19 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . .. . . . Cool bunch collision simulation by Andrei Seryi . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . It. also pitches the. beams vertically if they don’t hit head-on, and . . . . . . . . . . . . bunches cross. . generally makes a mess of. things .after the . . . . . Approximate the vertical restoring force on an electron as linear (note that change of variable to z = ct): y( z) ky( z) “Disruption parameter” Dy characterizes how strong this is: Dy k 3s 2 z so that y( z) Dy 3s 2 z y( z ) It’s a like a spring constant, scaled by sz2 to make it dimensionless. . . .. . . . . . . .. . 20 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . .. .. . . . Beam-beam effect improves luminosity . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Beam position monitors . . .. . . . . . . .. . 21 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 3 2. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . Field at ±/2 is times stronger than for a charge at rest. . . . . . . .. 2 . 2 2 4 . . 0r 1 sin . . . . . . .. . . . 1. . . . . . . .. . 2 . . . . . q . . . . . . . . . . . E and . . . . . 4.9105. . . . . .. . . . . . . . . . . . . . = .. . . . The field falls off appreciably when changes by ~1/. Field lines terminate on the image charge that travels along the beam pipe as a bunch as moves through the accelerator. . . .. . . . . . . .. . 22 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . Fields of a relativistic bunch inside a beam pipe . . . . . . . . . . . . . . . . . . . . . . . . --------------------- . . . . . . . . . . . . . . . . . . . . . . . . . . . r . .. . . . . . e+ Magnitudes of image and bunch charges are identical: 3.2 nC. 21010 e± (3.2 nC) .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 23 .. George Gollin, The International Linear Collider . . . I Physics P llinois --------------------- Field at the inner wall of a beam pipe with 2 cm radius is 2.8 MV/m. . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . Image. charge is concentrated in a .short . . . cylinder of . the same z extent as the . bunch. It travels along the vacuum pipe, keeping pace with the bunch. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . . . . . . . . . . .. . . . Image charge . . . . . . . . . . . . . . .. . . . . . . . . . . electrically isolated . . . “button” . . . . . . . . . .. . . . . . . . . . . . . . . . . . --. ---- . . -. --. . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . image charge .traveling . . . . along. inner wall of . . beam pipe with radius r . . . . . . . . . . . .. . . . . . . . . . signal cable signal current The 3.2 nC image charge is spread over a band of circumference 2r. A BPM button with diameter d will see ~0.5 nC d/r if a bunch is perfectly centered inside the pipe. t ~1 kV into 50 W .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 24 .. George Gollin, The International Linear Collider . . . I Physics P llinois I . . . . .. . . . Pickup electrode for a beam position monitor . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . Difference. . in signals increases.. . with offset . of the. bunch from . . . . . . . . . . . the . center of the beam pipe. Sub-micron resolution is possible. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . .. Position measurement with a BPM . (x, y) . . .. . . . . . . .. . 25 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . Here is one of the ~50 mm resolution BPMs we use. Our bunch charge is about 10% of an ILC bunch. . . .. . . . . . . .. . 26 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . We are using the 16 MeV e . . beam at the AØ photoinjector lab for damping ring kicker tests. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . Fermilab AØ BPM . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . I am used to thinking of systems designed to see single “minimum . . . . . . ionizing” particles (singly charged, relativistic particles): wire chambers, silicon tracking devices, scintillation counters, and photomultiplier tubes. Best resolutions of dozens of mm and hundreds of ps are typical for these kinds of devices. . . . . . . With so much charge present in a bunch, there are other ways to measure position and time that are new to me. . . .. . . . . . . .. . 27 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . .. . . . Thinking in new ways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . “Phase detector” for bunch timing . . . . . . .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 28 .. . George Gollin, The International Linear Collider . . . I . .. . Physics P llinois . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . .. The AØ photoinjector lab uses a 1.3 GHz RF system to power its . . . . . . . . . . . . . . . nicely synchronized to a master . accelerating structure. Everything is . . . . . . . . . . . . . oscillator that generates the original 1.3 GHz signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . We can determine timing of beam-induced events with respect to the RF clock with (to me) amazing precision. Here’s how… . . .. . . . . . . .. . 29 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . .. Using the AØ RF system for timing . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dispersion in a coaxial cable broadens the signal to a full width of ~1 ns. V t ~1 ns . . .. . . . . . . .. . 30 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . The device produces a very .. . . . . . . . . short bipolar signal when a . . bunch passes .through. it. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . Phase detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V . V .... . .. . . . . .. . . . . . . . . .. . . .. . . . .. . I Physics P llinois resonant structure . 1300 MHz AØ RF 1300 MHz . . V . . . . . . . . . . . . .. . phase detector signal . .. . . . .. . 1240 MHz. . . . . . . . . . . . . . .. resonant structure . . . . . . . . . . . . . . . . . . . . . . . .. . . Phase detector signal path . . .. . . . . . . . . . . . . V . . .. . . . . . . . . . . . . . . . . Low pass . . resonant structure .... . .. . . . . .. . . . . . . . . . .. . . .. . . . .. . . . 1300 MHz . . . . . . . . . . . . . . . . . . . . .. 60 MHz + 2540 MHz . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . RF mixer . . . . . . . I Physics P llinois . . 1300 MHz AØ RF . 1240 MHz . V . . . .. . . . . . . . . . . . . . . . resonant .. . . structure . . . . . . . . . . . . . . . phase detector signal . . . .. . . Phase detector signal path . . .. . . . . . . . V . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . sum . . Mixer output. . contains and difference frequencies. A low-pass .. . . . . . . . . . . . filter. transmits only the 60 MHz component. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . sin 1300t sin 1240. t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . 1 1 cos 1300 1240 t cos 1300 1240 t 2 2 Note that appears unaltered in the 60 MHz term. = 90° in the 1240 MHz signal (202 picoseconds) maps into = 90° in the 60 MHz signal (4.17 nsec). Timing accuracy is 1240/60 times better than scope precision. . . .. . . . . . . .. . 33 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . .. . . . Doing almost nothing yields 100 ps precision . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . Down-mixed signal voltage . . . . . . . . . . . . . . . . . . . . . . . . 20 ns time How well we can determine the relative start times for each of the displayed signals? (Probably to better than 100 ps.) Divide by 1240/60 to obtain bunch timing precision. We think we’re going to obtain a bunch timing accuracy of ~5 ps or better. . . .. . . . . . . .. . 34 .. George Gollin, The International Linear Collider . . . Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . .. . . . . . . I . . . . . . . . . . . AØ data . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Radiation from accelerating charges . . .. . . . . . . .. . 35 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . observer:. . time t . . . . . . . . . . . . Retarded time: t t r rQ t c . . . . . . . . . . Potentials measured by the observer depend on where the moving charge was, not where it is right now: r rQ t , not r rQ t . . . .. . . . . . . .. . 36 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . .. r . . . . . . . . . .. . . . . v t rQ t . .. . rQ t . . . . . . . . . .ˆ t .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . .. . . . . . . Retarded time is (distance to charge) / c . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . r r c 1 r , t. 3 . V r , t . .d r 4 0 r r all space . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . and scalar . . the vector Including potentials are . . retardation, .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . m0 J r , t r r c 3 Ar ,t d r 4 r r all space It is beautiful in its simplicity. But we differentiate the potentials to calculate E and B, so retardation effects complicate the calculation: . . .. . . . . . . .. . 37 .. George Gollin, The International Linear Collider .... . .. . . . . .. . . . . . . . . I Physics P llinois E V A t . . . . . Calculating potentials using retarded time . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . solution includes The result of the differentiation is remarkable: the . . . . . . . . . . . . . . . . electromagnetic radiation. . . . . . . . . . . . . . ˆ . . . . . . . . . . . . . . . . Qa 3 2 r rQ 4 0c 1 ˆ v c . 1 1 r only . .. . . . . . . E . . . . . . . . v For relativistic motion the 1 ˆ v c term dominates the angular dependence so that radiation is emitted primarily along the direction of motion. 3 The rms width of the radiated power is rms = 1/. . . .. . . . . . . .. . 38 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . .. . . . Differentiating the potentials to obtain E and B . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . .. . . . . . . . . Electromagnetic radiation, in particular when a v . . . . . . . . . Calculate power radiation . .radiated in the usual way. For. synchrotron . . . . . . . . . . a v .. . . we. have . . . . . . . . . . . . . . . . .. . Radiated power (GeV/sec) is P 4.23 103 E 4 . . . . . . 2 E is the electron’s energy (GeV), is its trajectory’s radius of curvature. Radiated energy (GeV) per orbit is E 8.85 10 E4 .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 39 .. George Gollin, The International Linear Collider . . . I Physics P llinois 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. .. . . use the same magnets to build a bigger . energy… . If we ring at higher . . . . . . . . . . .. . . . . . • ring size: E. • synchrotron power loss per bunch: P E4/2 • number of bunches in ring: N . . . . . . . . . . . Cost ~ ($¥€ per unit length) E + ($¥€ per MW RF) E3 Linac cost scales linearly with E, but bunches only collide once. . . .. . . . . . . .. . 40 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . Linear vs. circular machines . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Beamstrahlung . . .. . . . . . . .. . 41 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . Beam-beam induced synchrotron radiation is called beamstrahlung. . . . . . . . . . . . . . . Let’s. estimate its importance using classical electrodynamics: . . . . . . . . . . B B . . B . . . . . . . . . . .. . . . . . . . . . . . . . . .. Vertical oscillations cause beamstrahlung . . . . . . . . . . ............................................................ ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................................................... ......... ....................... . . . . . ................... ......................... ........ ................................................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . e+ B B B B ~ 500 T; radius of curvature of a 250 GeV e+ is 1.66 m (!!) . . .. . . . . . . .. . 42 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . An electron takes about 1.7 ps to pass through the positron bunch. So it might lose as much as 10 GeV due to beamstrahlung. (!!) Beamstrahlung broadens the energy spectrum at the point of annihilation and adds to the uncertainty in c.m. energy of a collision. A real calculation yields E 7.0 GeV, n 1.65 e http://www.slac.stanford.edu/econf/C980914/papers/F-Th24.pdf . . .. . . . . . . .. . 43 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . 6 10 GeV/sec .. 12 . . . . . . . . . . . 2 . . . .. . . . .. . P 4.23 10 E . . 3 4 . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . .. .. . . . Beamstrahlung radiated power . . . Radiated power (GeV/sec) is . . . . . . . . . . . . . . . . . . . . . . . . . . Characteristic beamstrahlung photon energy . . . . . . . . . . . cone. of . synchrotron . radiation . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . 1/ . . . . . . . . . Make a rough . estimate .. . . of the typical . . . . . . . beamstrahlung photon energy using . . . . . . . classical electrodynamics. . . . . . . . . . . . . . . . .. . . . .. .. . . . . . . 1/ observer sees all radiation emitted between these two points Observable radiation is emitted along an arc of length s = /r = 2/(). It arrives during a time interval t = s(1/v – 1/c) = / (c 3). c = 2/t and Ephoton ~ hc yields Ephoton ~ 8.7 GeV .... . .. . . . . .. . . . . . . . . . .. . . .. . . . .. 44 . . George Gollin, The International Linear Collider . I Physics P llinois Exact (QED) expression for c is 50% larger. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . This is not a good thing: photons mixed in with. the colliding . . . . . . . + . . . . . . bunches allow large numbers of soft e e pairs to swirl out from the . . . . . . . . . . IP. . . . . e e . . . . . . . .. . . . . . . . . . . . . . . . . e e e e e e e e e e Use largest possible magnetic field in the detector to confine e to small radii so they don’t wipe out the vertex detector. Under discussion: SiD (“Silicon Detector”) with 5 T field, 5 m diameter, 5 m length. . . .. . . . . . . .. . 45 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . Beamstrahlung-induced problems .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Beam dynamics, briefly . . .. . . . . . . .. . 46 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . with exactly A. single beam particle the. “right” momentum and . .. . . . . . . . . . . . . . initial position travels along the (closed) reference orbit in an ideal . . . . . . . . . . . . . . accelerator. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Local “wavelength” of oscillations varies along the reference orbit. . . Orbits of particles that remain inside the machine’s acceptance will oscillate around the reference orbit. . . . . . reference orbit (gray line) particle orbit oscillates around reference orbit l ~ separation between red marks. . . .. . . . . . . .. . 47 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . .. . . . Reference orbit . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . particle orbit n = 22.75 .... . .. . . . . .. . . . . . . . . 48 . . . George Gollin, The International Linear Collider .. . . . . ds s .. . . . . . . . . . . . . . . I . reference orbit for s the path length along the reference orbit. Physics P llinois . . . . More precisely: . .. . n . . . . . ~ l/2 . . . . . .. . . . . . . . . . . . . of oscillations . .. . . The number around the .reference orbit in one turn is. . .. . . . . . . . . . . . . called the tune of the accelerator. Shown: n = 22.75. . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . .. . . . . Tune and . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . x . . . . . . . . . . . . . . . . Liouville’s theorem: without dissipative effects the area of the ellipse will not change. . . The shape of. the ellipse . varies from place to place along the reference orbit, but its area remains constant. . . . . . . . . . . x x x x Beam’s emittance is the area of the ellipse. .... . .. . . . . .. . . . . . . . . . . . 49 .. . George Gollin, The International Linear Collider .. . I Physics P llinois x .. . . . . . . . . . . . x . is the distance from. the reference orbit. x and its. ..first derivative x . . .. . . . . . . . . . . .phase plane. . . . will lie on an ellipse in the x, x . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . Phase space; Liouville’s theorem . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . x . . . . . . . . . . . . . . . . . . . . . . . . . Normalized emittance is defined as x . . . . . . . . .. . . . . . . . . . . . . . . . . . x The ILC’s normalized (vertical) emittance goal is y = 0.04 mm.mrad yielding a luminosity L = 21034 cm-2 s-1. . . .. . . . . . . .. . 50 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . The beam’s emittance (x) is the area of the ellipse. Since x. is . . . . . . . . . . . . dx/ds, x is an angle, not a velocity. . . . . . . . . . . . . . . .. . . . .. . . . . . . . . .. . . . . . .. . . . . . . . . . . . .. . . . . Emittance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . …is. possible if we cause the beam to lose energy. (That makes . the . . . . theorem not applicable.) . . . . . . . . . . . . . .. . . . . .. . . . . . . We can collapse the ellipse considerably, as is done in a damping ring. More about this later. . . .. . . . . . . .. . 51 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . Beating Liouville’s theorem… . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . source .... . .. . . . . .. . . . . . . . . . . . . . . .. . . . . . . .. . 52 .. . George Gollin, The International Linear Collider . . . . . . . . . . . . . . . Polarized . . . . . . . e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . I . . . . . .. . . . . . Physics P llinois . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Electrons from the photocathode are accelerated to ~120 kV, then bunched, accelerated more, and eventually sent to a damping ring to reduce the bunch emittance. laser beam Space charge effects dominate the emittance coming out of the electron source: y ~ 500 too big. ~2 cm electrons accelerating voltage .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 53 .. George Gollin, The International Linear Collider . . . I Physics P llinois photocathode . . . . This is where begins: an intense laser beam blasts a .everything . . . . . . . . . . . liberate “strained GaAs” photocathode to electrons. . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . .. . . . e- source overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . • circularly polarized . . . . . . . . . . . . . • Epulse. ~ 2 mJ (81012 ) . . . . .. . . . . . . . . . . . • timing structure: 2820 pulses spaced 337 ns apart; repeat this at 5 Hz. . . .. . . . . . . .. . 54 .. George Gollin, The International Linear Collider .... . .. . . . . .. . . . . . . . . I Physics P llinois http://www.astec.ac.uk/id_mag/BCD/ILC_source_R&D_plan.pdf . . . •. 800 nm wavelength. to. match .photocathode band structure . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . beam. Ti:Sapphire, 90% circularly polarized . . . .. . . . . .. . . . . . . . . . . . .. . . . . Laser . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . .. . . . . 55 .. . George Gollin, The International Linear Collider .. . . . . http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-11686.pdf . . . . . . . . . I Physics P llinois . . . http://www.astec.ac.uk/id_mag/BCD/ILC_source_R&D_plan.pdf . . . . . . . . . with .slightly different . . substrates By. growing lattice. sizes it . crystals on .. . . . . . . . . . . . . . . is possible to do “band gap engineering.” Photon polarization is well . . . . . . . . . . . . . . preserved by ejected electrons. 80% seems feasible. . . .. . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . . . . .. . . . . Photocathode . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . source .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 56 .. . George Gollin, The International Linear Collider . . . . . . + e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . I . . . Physics P llinois . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . .. . . . . . . . . . . . . . . . . 150 GeV electrons from a helical . . . . linac . will pass through . . the main . .. . . . . . . . . . . . undulator, emitting circularly polarized synchrotron radiation. Each . . . . . . . . . . . . . electron loses 3.23 GeV in the process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . Helical undulator positron source . . Photon beam power is. ~150 kW; spot size on a 0.4 radiation length conversion target is 0.75 mm. . collection 150 GeV e- helical undulator magnet 100 - 200 m conversion Positrons from e+e- conversions in the target are captured and accelerated to 5 GeV for injection into a damping ring. . . .. . . . . . . .. . 57 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . http://hep.ph.liv.ac.uk/~ibailey/helical/helical_hep2005_cockcroft.pdf .... . .. . . . . .. . . . . . . . . . 58 . . . George Gollin, The International Linear Collider .. . . . . . . . . . .. . . . I . .. . Physics P llinois . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . .. Several designs being considered. Here is an NdFeB permanent . . . . . . . . . . . . . . magnet version with a 1.4 cm period and 0.8 T field. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . .. . . . Undulator magnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . length of the. Beam electrons move in narrow helices along the . . . . . . . . . . . . undulator. For 1 cm spatial period, orbit “corkscrew” period is . . . . . . . . . . . -11 sec. . . 3.3310 . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . .. Photon energy from the undulator . Radiation emitted during one turn arrives in an interval 1 1 11 1 1 cm 3.33 10 2 1.94 1022 sec v c 2 Using = 2 / and Ephoton ~ h yields Ephoton ~ 22 MeV. Note that Ephoton ~ 2 so that high “drive beam” energy is necessary. . . .. . . . . . . .. . 59 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . photon. . Positrons will tend to exhibit the polarization of the parent . . . . . . . . . . . The . ILC baseline. design. document discusses the possibility of an . . . . . early upgrade (longer . undulator) to obtain 60% polarization in the . e+ beam. . . . . . . . . . . . . SLAC E166 took data in 2005 to study production of polarized e+ using an undulator; it worked. “No surprises,” but they are still analyzing data from their runs. Emittance from the positron source: y ~ 500,000 too big. . . .. . . . . . . .. . 60 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . Polarized positrons! . . .. . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . 61 .. . George Gollin, The International Linear Collider .. . I Physics P llinois . . . .. . . . . . . . . . . . . Emittance reduction in the ILC damping ring .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . emittances. . of the e+ and The damping rings need to reduce the . e . . . . . . . . . . . . . beams considerably in ~ 0.1 second. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . Also, the damping ring needs to cool all 2820 bunches at once, then . extract them to the main linac with 337 nsec bunch spacing. . injected x, y extracted x extracted y electrons 10-5 m 8 10-6 m 0.02 10-6 m positrons 10-2 m 8 10-6 m 0.02 10-6 m The damping ring may be the ILC’s most challenging subsystem. . . .. . . . . . . .. . 62 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . .. . . . Damping ring issues . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . .. Since synchrotron radiation is nearly parallel to the particle’s . . . . . . . . . . . . . . longitudinal and transverse . . velocity, radiation reduces both the . . . . . . . . . . . . . orbit. momentum components of the particle relative to the reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RF system only restores the longitudinal component. RF pz px after radiation after RF .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 63 .. George Gollin, The International Linear Collider . . . I Physics P llinois before radiation . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . .. Damping via synchrotron radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . .. Damping time is inversely proportional to how rapidly the particle . . . . . . . . . . . . . . . loses . . . energy via radiation: . . . . . . . . . . . . . . . . . . . . . . . . . . . 2E D 3 P E . 2. . . . . . . . . . . . . . . . . . . . Small radius (hard bend) reduces damping time. But there is a minimum (equilibrium) horizontal emittance that can be obtained due to the discrete nature of photon emission. Damping ring uses wiggler magnets to speed up the process. Even so, vertical emittance takes 8D to drop sufficiently. . . .. . . . . . . .. . 64 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . .. . . . Damping time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . Original (TESLA) design called for a 17. km circumference damping . . . . . ring (!!) . . . . . . . . . “Dogbone” shape would put most of it in the main linac tunnel but: • access for repairs is not possible when linac is powered • stray fields from RF system klystrons may disrupt DR beam Why is it so long? Because… . . . . .. . . .. . . . .. 65 . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . Damping ring designs . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ILC main linac beam:. . . . .. . . .. . . . . . . . . . . . . • 2820 bunches, 337 nsec spacing (~ 300 kilometers) . . . . . . . . . . . . . • Cool an .entire. pulse .in the damping rings before linac injection .. . . . . . . . . . . . . . . . . . . . .. . . . . . . .. .. . . Damping ring beam (TESLA TDR): • 2820 bunches, ~20 nsec spacing (~ 17 kilometers) • Eject every nth bunch into linac (adjacent bunches are undisturbed) Kicker speed determines minimum damping ring circumference. Large circumference is worrisome. Tricky beam dynamics? Wigglers used to cool beam: ~400 m of them. . . .. . . . . . . .. . 66 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . Original design: 17 km circumference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . If so, a smaller damping . ring would be possible. . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .figured out What if we a. faster kicker? .. . . how to make . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . The problem with the kicker: it is hard to turn on/off quickly. Two approaches we’re exploring (UIUC + FNAL + Cornell): 1. brute force: robust, faster HV switch. 2. a new kind of kicker that is always running. In tandem with kicker studies we’ve been investigating a damping ring lattice for a 6 km ring. .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 67 .. George Gollin, The International Linear Collider . . Physics P llinois . I A 6.6 km ring is now the baseline recommendation! . . Thinking differently . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . 68 .. . George Gollin, The International Linear Collider .. . I Physics P llinois . . . .. . . . . . . . . . . . . ILC damping ring stripline kicker .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . pulses traveling .. A bunch “collides” with electromagnetic in the . . . . . . . . . . . . . . . . opposite direction inside a series of traveling wave structures. Hard to . . . . . . . . . . . . turn. on/off fast enough. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fast kicker specs (à la TESLA TDR): • B dl = 100 Gauss-meter = 3 MeV/c (= 30 MeV/m 10 cm) • stability/ripple/precision ~.07 Gauss-meter = 0.07% . . .. . . . . . . .. . 69 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . Brute force: stripline kicker . . .. . . . . . . . .. . . . . . . . . . . . .. . . . .. . . . . .. . . . UIUC/FNAL/Cornell stripline kicker studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . Start with a simple kicker whose properties are calculable and .can be. . .. . understood independently of those of the A0 electron beam. . . . . . . . . . . . . Most important: how well can we measure a device’s amplitude and timing stability with the A0 beam? A0 runs at 1 Hz, so performance demands on DAQ and offline analysis processing are not severe. . . .. . . . . . . .. . 70 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measuring electrode geometry before final assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .... . .. . . . . .. . . . . . . . . . . . . . . .. . . . . . . .. . 71 .. . George Gollin, The International Linear Collider . . . . . . . . . . . . . . . I . .. . . .. . Physics P llinois . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . .. . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . .. . . . . . . .. . . 72 .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . I . . . . . Physics P llinois . . . . . . .. . . . .. . . Final assembly of the kicker . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . 16 MeV electron . . . beam, good spot size, emittance. . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . very . First significant data were written August 11, 2005. That was a . . . . . good day!* . . . . . . .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 73 .. George Gollin, The International Linear Collider . . . . . I Physics P llinois *You have no idea… come to my other talk. . . . . .. . . . Test it in the FNAL AØ photoinjector beam . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . .. . . We test the stripline kicker in Fermilab’s 16 MeV e- beam. 100W device, 1 cm gap, 15 mrad deflection. . . .. . . . . . . .. . 74 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . Stripline kicker in A0, looking upstream . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . .. . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . Chris Jensen and colleagues at FNAL built it. for us. . . . Physics P llinois . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . I . . . . . . . . . . . . . . . . . .. . . . . . .. . . HV pulsers . . . . . . . . . Start with. . a Fermilab linac chopper HV pulser: ±750 V. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .... . .. . . . . .. . . . . . . . . . . . . . . . . . . 76 .. . . George Gollin, The International Linear Collider .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . Physics P llinois . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . I . DAQ uses an oscilloscope as a transient digitizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . . . . . . .. . . .. . . . .. 77 . . . George Gollin, The International Linear Collider . . . . . . . . . . . . . . . . . . . . . . . . I . . .. . Physics P llinois . .. . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . Event display, 10 pulses . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 78 . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . .. . . . . . .. . . . . . . . . I Physics P llinois . . . . . FID Technology F5201 Pulser. . Parameters . . . . . .. . . . . . . . . . . . . • Dual channel: +/-. 1kV . . . . . . . . . . . • 0.5% - 0.7% amplitude stability . . . . . • 0.7 ns rise time, 2.0 ns top of pulse, 1.2 ns fall . time • 3 MHz max. burst rate, 15 kHz max. average rate • <20 ps timing jitter . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . .. . . . . . . . . . FID pulser: much faster, but stability unclear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . . . . .. . . .. . . . .. 79 . . . . . . . George Gollin, The International Linear Collider . . . . . . . . . . . . . .. . . . . . . . . . . . . I . .. . . .. . Physics P llinois . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . FID HV: ±1 kV, few ns length . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . data . . . . .. . . .. . . . .. llinois .... . .. . . . . .. . . . . . . . I prediction . Nothing is calibrated yet, and we have programming artifacts Physics Pto remove… . . . . .. . . . It kicks the beam! First FID HV pulser data . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . As measured after the A0 stripline kicker . . . . .. . . .. . . . .. 81 . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . It broke. Pulse train failure: . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . We . tried to generate pulse trains with ILC-like timing structure.. .. . . . . . . . . . . . . Pulser burst mode appears to have failed after allowing the FID to run over night. • Observed 1st pulse parameters still near nominal • Trailing pulses do not have stable amplitudes Cornell met with FID engineer to discuss evaluation and repairs. Pulser was repaired, then broke after running for a month. Improvements may make it more reliable. . . . . .. . . .. . . . .. 82 . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . Characterizing to beam using UIUC DAQ. system . kick . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . .. . . . Present Status . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . . .. . . . . . . .. . 83 .. George Gollin, The International Linear Collider . . . . . . . . . . . . . . . . . I . . . . Fourier series pulse compression kicker . . . . . . . . . . . . . . . . . .. . Physics P llinois . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . Fields when kicker is empty of beam are irrelevant. . . . . . . . . . . . . . . . . . . . . . . kicker . . . . . .. . . . . . . . . conventional . . . . . . . . . . . Kicker field needs to be . . . . zero. when unkicked . bunches pass through.. .. . . . . . . . . . . . .. . . . . . .. . . . . . . . . . . . damping ring beam kicker field vs. time Synthesize kicker impulse from Fourier components of something with good peaks and periodic zeroes. Fourier kicker damping ring beam Kicker is always on. .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 84 .. George Gollin, The International Linear Collider . . . I Physics P llinois kicker field vs. time . . .. . . . Since it’s hard to turn on/off, why not leave it ON all the time? . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . k=N k . . . . . . . . . 2N kicker This is what we’re actually studying now, but with N = 60 and = 10: ~1.8 GHz ± 10% bandwidth -50 50 100 150 -0.5 85 . . . -100 . . -150 . I Physics P llinois 0.5 .... . .. . . . . .. . . . . . . (Graph uses N = 16, = 4.) fields 1 .. . . . ak .. . . . . . . . . . .. . . . . . . . . . . . . bb bbbbbbbbbbbb .. . . . . . A. high-frequency the .fractional . .modulated signal: this reduces . . . . . . . . . . bandwidth. . . . . . . Fourier amplitudes . . . . . . . . . . . . . . . . . . . . . .. .. . . . . . A function with good peaks and zeroes . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . injection/extraction . . . . . . . . . . damping . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . the . We. don’t want . . . . . beam . to go through . . . the kicker until we’re . ready to extract. . . . . . .. . . . . .. . . . . Fourier series kicker would be located in a bypass section. kick While damping, beam follows the upper path. During injection/extraction, deflectors route beam through bypass section. Bunches are kicked onto/off orbit by kicker. . . .. . . . . . . .. . 86 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . Damping ring operation with an FS kicker . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Construct a. kicking pulse from a . sum of. its Fourier . . .components.. . . . . Combine this with a pulse compression system to drive a small number . . . . . . . . . . of low-Q cavities. . . . . . . . . . . . . . . . . Illinois, Fermilab, Cornell are involved. . . . . .. . . .. . . . .. 87 . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. .. . . . . . . Fourier series pulse compression kicker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Into wave guide last . 8 8 7 1 9 2 1.3 10 2 9 3 10 3 9 4 10 4 9 5 10 9 5 GHz .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 88 .. . George Gollin, The International Linear Collider . . . . . . . 0 10 . . . 10 . . 5 . 10 . 1 . 10 . . . . . 1.5 . .. 8 0 I . 0.5 c Physics P llinois . 10 . . . . . 2 8 . . 10 . . . 2.5 . Into wave . guide first . . . . . . . . . vs . frequency . . .. . . velocity . . . . group . c . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . .. . . . . . . . Group velocity vs. frequency . . . . . 1.3 GHz cutoff frequency wave. .guide . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . upstream end of waveguide fields including cavity . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . kicker . cavity . . . . (dispersive) wave. guide . . . . . . . . . . . .. . . . . . . . . . Note that peak field is about .018 here, in comparison with 1.0 inside cavity. . . . . . . . . Field. at upstream end . of the wave guide. . function. . RF . generator. amplifier . . . . . . . . . .. . . . .. . . . response 0.015 0.01 0.005 Pulse compression, plus energy storage in the cavity! 1.5 10 -7 2 10 -7 2.5 10 -7 3 10 -7 3.5 10 -7 4 10 -7 -0.005 -0.01 .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 89 .. George Gollin, The International Linear Collider . . . I Physics P llinois -0.015 . . . . . . . . . . . . . Field at entrance to the wave guide .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maximum amplitudes: •entering ~0.016 .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 90 .. . I Physics P llinois ~0.1 . . •exiting . . . . . . . . . . . . . . . . . . .. . . .. . Pulse compression! . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . Waveguide compresses pulse . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. kicker . . . . . . . . . . . . . . kicker . cavity . fields 0.75 Field inside cavity . . 0.5 kicker fields , 10 ns 1 0.25 0.5 -1.5 10 -7 -1 10 -7 -5 10 -8 5 10 -8 1 10 -7 1.5 10 -7 -0.25 -1 10 -8 -5 10 -9 5 10 -9 1 10 -8 -0.5 -0.5 -0.75 . . .. . . . . . . .. . 91 .. George Gollin, The International Linear Collider .... . .. . . . . .. . . . . . . . . I Physics P llinois ±10 ns -1 . . . . . . . (dispersive) wave. guide . . . . .. . . . . . . . . .. . . . . . . . . . . . function. . RF . generator. amplifier . . . . . .. . .. . Cavity center. frequency is 600 times. linac frequency, 10 times damping ring frequency. . . . . . . . . . . . . . Signal inside the .kicker . cavity . . . . . field for Kicker cavity . . . . . ~6. ns. bunch spacing. . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . We’ve been borrowing lab space in an instructional lab in ECE . .. . (Electrical and Computer Engineering) for some of our work. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . . . . . . . . . . . .. . . . RF work at UIUC . . . . . . . . . . . . We do not have previous RF engineering experience, so we’re learning as we go. We discuss things with Fermilab’s RF group. When we are further along, they’ll drive south to spend a few days at UIUC working with us. . . .. . . . . . . .. . 92 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (It’s actually aluminum downspout.) . . . . . . . .. . . . . . . . . . . . . . . . . . Since then we’ve borrowed real waveguide from Fermilab. .... . .. . . . . .. . . . . . . . .. . . . . . . .. . 93 .. George Gollin, The International Linear Collider . . . I Physics P llinois using aluminum downspout as an inexpensive Lband waveguide . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . Cheapest source . of. L-band . . . . . waveguide: Lowe’s! . . . . .. . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . .. . . . . . . In the RF lab at UIUC . . . . . . . . . . . . . . . . Measuring cut-off frequency in “L-band” downspout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .... . .. . . . . .. . . . . . . . . . . . . . . .. . . . . . . .. . 94 .. . George Gollin, The International Linear Collider . . . . . . . . . . . . . . . I . .. . . .. . Physics P llinois . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . Cut-off frequency and complicated frequency structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . RF signal out: notice cutoff frequency . . .. . . . . . . .. . 95 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . . . . . . . . . . .- . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . Initial studies: MeV e ) .for . use . . . Fermilab A0 photoinjector .beam (16 . . . . . . . . . studies: . . . . . . . . . . . . . . . . . 1. concept and design studies of FSPC kicker . . . . . . . . . .. . . 2. build a fast, simple strip line kicker 3. use the stripline kicker to study the timing/stability properties of the AØ beam 4. build a single-module pulse compression kicker 5. study its behavior at AØ 6. perform more detailed studies in a higher energy, low emittance beam (ATF??) . . .. . . . . . . .. . 96 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . Fermilab/Illinois activities .. . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Main linac . . .. . . . . . . .. . 97 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . Cryogenic “unit . . . . length” is ~2.5 km . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TTF . . . . .. . . .. . . . .. 98 . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . (From TESLA TDR) . . . . . . . . .. . . . . . . . . . . . . . . . . TESLA main linac . . . .. . . . . .. . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . ILC main. linac . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . • 500. GeV requires 23.4 MV/m gradient (theoretical limit is. 50 MV/m) . . . . . . . . . . . . .. . . . . . . . . . . . . . • Niobium, 1.3 GHz cavities . . . . . . . . . . . . . . . . . . (From TESLA TDR) . . . . .. . . .. . . . .. 99 . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . .. . . . . . . . . . . . Accelerating structures: . . . .. . . ILC rf cavities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 .. . . . . . . . . . George Gollin, The International Linear Collider .. . . . . . . . .... . .. . . . . .. . . . . . .. . . . I Physics P llinois . . . . . . . . . . . . (M. Liepe, http://www-conf.slac.stanford.edu/alcpg04/Plenary/Wednesday/Liepe_ColdMachine.pdf . ) .. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . Recent progress is . even better:. . 42 MV/m now! Single crystal . . . .. . . . . . . . . . . . cavities being manufactured (fewer domain boundaries). . . . . . . . . . . . . . . . . . . . . . .. . . . . . .. . . . . . . . . .. . . . RF cavity gradients . . . . . . . . . . . . . . . . . . . . . . . . (click to play movie) .... . .. . . . . .. . . . . . . . . . . . . . . . . I Physics P llinois . Long bunch spacing (337 nanoseconds) is necessary. . 101 . . . . . . . . .. . . . . . . . .. . . . .. .. . . . . . . . . Bunch length ~20 picoseconds so lots of modes can be excited. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . persist. . High-Q (superconducting) structures: induced fields .. . . . . .. . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . .. . Wake fields . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Physics . . .. . . . . . . .. . 102 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . • . Electroweak. symmetry breaking is mediated by something . that . .. . almost certainly will reveal itself in the 100 GeV . to 200 GeV mass . . range. . . . . . . . . . . . • If nothing is there, the wheels come off the bus. Everything goes crazy. • Even if there’s a higgs, there are enormous cosmological constant problems without something else (SUSY?) . . .. . . . . . . .. . 103 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . We. have all heard this many times: . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . Physics at the ILC . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . .. . . . . . . .. . 104 .. . . . . . . George Gollin, The International Linear Collider . . . . . . . .. . . . . . . . . . I Physics P llinois . . . . The role of LEP in . refining our understanding of the Standard Model is an example. . . . . . . . . . Both have been necessary. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . and discovery Precision measurements experiments: . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . Physics at the ILC . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . …is mixed. Our confidence in our. predictions is influenced . . by our . . . . . . . optimism! . .. . . . . . . . . . . • SU(5) and proton decay . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . Our success at predicting the unknown… .. . . • value of / in K decay (direct CP violation) We will need both LHC and ILC to understand the physics of electroweak symmetry breaking . . .. . . . . . . .. . 105 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . . . . . . . .. . . . . . . .. . 106 .. . George Gollin, The International Linear Collider . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . . . . . In stock and on sale! . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . . I . We may be closer than we think .. Physics P llinois . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . Dark matter: 22.6% Standard Model Physics: 4.4% We will need a goodly amount of data to understand things. . . .. . . . . . . .. . 107 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . energy: . 73% Dark . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . Who are we kidding? .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . Politics . . .. . . . . . . .. . 108 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. “The key to 'revolutionary' social change in modern societies does not therefore depend, as Marx had predicted, on the spontaneous awakening of critical class consciousness but upon the prior formation of a new alliance of interests, an alternative hegemony or 'historical bloc', which has already developed a cohesive world view of its own.” (quoted by M. Stillo from . . . . . . . . . . . .. . . . .. 1. The evolution of events is chaotic, not smooth. . . . . . . . . . take . We to . quickly . . must be ready to act . . . . . . . advantage of opportunities that may arise. .. . . . . . . . . . . . . . . . . . . . . . . .. . . . .. . . Will it ever get built? . Antonio Gramsci 1891 – 1937 Prison Notebooks (“Hegemony”) Williams, 1992: 27 in http://www.theory.org.uk/ctr-gram.htm) . . .. . . . . . . .. . 109 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . 1. . “RIA for. .Illinois”. task force run by the Illinois Department for . . .. . . . . . . . . . and Economic Opportunity . Commerce (DCEO). Argonne, . . . . . . . . . . . . . . . Fermilab, and Illinois Universities had been major participants. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . 2. Considerable strengthening of the Fermilab – Argonne alliance has taken place in the last year or two. 3. RIA, ILC, proton driver, and APS direct injector linac are all superconducting machines that could be built in Illinois. DCEO appeared to understand that a wider scope for its RIA advocacy is appropriate. This is still evolving. 4. This was a near-miss: DCEO lost interest when RIA RFP was postponed. But we learned something from this. . . .. . . . . . . .. . 110 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . State of Illinois efforts . . . .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . Office of Science has. now stated. that the. U.S. proposal to become the. . . . . . .. . . . . . . . . . . . . ILC host country will put forth Fermilab as the host laboratory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Apparently OS would like to see a significant reduction in total project . . . cost relative to what we presently expect ILC to cost. . . . . Recent news from Ray Ohrbach, Director, Office of Science of DOE. If we can: • show that ILC has good support in HEP (and other physical science) community • demonstrate that US share will be ~ $3.5B Then ILC will become a presidential initiative for a 2011 construction start. . . .. . . . . . . .. . 111 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . .. . . . The federal scene . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . University R&D . . .. . . . . . . .. . 112 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . .. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . Accelerators are BIG, EXPENSIVE devices. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Many university HEP groups have concentrated on detector projects, . . . . perhaps because they believe these are: • more suitable in scale for a university group • more practical, given their prior experience in detector development. . . . Is this really true? Should university groups stay away from accelerator physics projects? . . .. . . . . . . .. . 113 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . .. . . . Can university groups do accelerator physics? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . are interesting, important projects .whose scope is ideal . There for a . . . . . . . .. university .group. . . . . . . . . . . . . . . . . . .. . . . . The (inter)national labs welcome our participation and will help us get started, as well as loaning us instrumentation. Many projects involve applications of classical mechanics and classical electrodynamics. These are perfect for bright, but inexperienced undergraduate students. The projects are REALLY INTERESTING. (Also, it’s fun to learn something new.) . . .. . . . . . . .. . 114 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . Of course university groups can do accelerator physics! . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . January, 2002: . . . . . . . . . . . . . .. • FNAL .was focused on Run II problems. LC wasn’t on the lab . . . directorate’s radar. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. .. . . . . Engaging the university HEP community . . . . • most university LC groups were already affiliated with SLAC; most were doing detector simulations. • there was little planning underway to attract new groups (for example, with Fermilab orientations). That wasn’t good! . . .. . . . . . . .. . 115 .. George Gollin, The International Linear Collider . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8/02 . . . . . . . . . . . . . . . . . . . . . . . . . . 9/02 9/02 separate accelerator and detector committees review proposed work for both agencies 9/02 UCLC proponents revise project descriptions 10/02 10/02 . . . . .. . . . . 116 .. . . George Gollin, The International Linear Collider .... . .. . . . . .. . . . . . .. . . proposal coordinators create new document combining revised LCRD and UCLC projects, then transmit to DOE and NSF. . . . . . . . UCLC proponents write “project descriptions” proposal coordinators create one unified document combining LCRD and UCLC projects LCRD proponents revise subproposals Physics P llinois . . . . . . . . . .. . LCRD proponents write “subproposals” . . . . . . 7/02 . . . . . . . . . . . ALCPG working group leaders offer. suggestions . . . . for revision, collaboration with other . . groups, etc. . . I . . . UCLC (NSF) proponents write . . short project. . descriptions . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . .. . . . . . . . . . . . . .. . We organized ourselves LCRD (DOE) proponents write . . . . . . short project descriptions . . . . . . . . . . . . . . . . . . 71. new projects . . . . 47 . U.S. universities . . 6 labs . . 22 states 11 foreign institutions 297 authors 2 funding agencies two review panels two drafts 546 pages 8 months from t0 . . . . . . . . . . . .... . .. . . . . .. . . . . . . . . .. . . . . . . .. . 117 .. *planning grant only . . . . . . . Funded by NSF* and DOE . . . . . . . . . . . . . . . . . . . . . . . . . …renewal submitted November 2003 …third year submitted February 2005 …fourth year submitted January 2006 • • • • • • • • • • • .. . . . I . . . . .. . . The result: . .. . Physics P llinois . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . .. . . . The result, first year . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . University . groups won’t engage until they see that there is . . genuine interest from DOE and NSF in supporting .ILC R&D. . . . .. . . The ILC R&D budget went up $30M this year. An unimaginative approach would be to have all of it flow to the national labs and none to the universities. The unimaginative approach would be irresponsible and would crash the U.S. HEP program. Comments of the speaker… . . . . .. . . .. . . . .. 118 . . . I Physics P llinois .... . .. . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . Ohrbach’s .message was also a warning. . . . .. . . . . . . . . .. . . . . . . .. . . . . . .. . . . . . . . . . . . . . . . . .. . . . It’s time to get serious . . . . . . . . . .