Transcript Pergine Slides - Istituto Nazionale di Fisica Nucleare

Measurements, ideas, curiosities
Possible scenarios and milestones
for the LHC luminosity upgrade
Complement to the presentation on LHC performance & upgrade
F. Ruggiero
CERN
Univ. “La Sapienza”, Rome, 20–24 March 2006
Scaling of electron cloud effects
blue: e-cloud effect observed
red: planned accelerators
more ‘ultimate’
bunches
longer fewer more
intense bunches
experience
at several
storage rings
suggests that
the e-cloud
threshold
scales as
Nb~Dtsep
possible LHC
upgrades
consider
either
smaller Dtsep
with constant
Nb, or they
increase Dtsep
in proportion
to Nb
2
Electron-cloud build-up in the LHC
•
Beam synchrotron radiation is important
• provides source of photo-electrons
•
Secondary emission yield (SEY) d(E) is important
• characterized by peak value dmax
• determines overall e– density
•
e– reflectivity d(0) is important
• determines survival time of e–
•
•
Bunch intensity Nb and beam fill pattern are important
Main concern: power deposition by electrons on the cold beam screen
F. Ruggiero
CERN
LHC beam performance and luminosity upgrade scenarios
LHC arc heat load vs. intensity, 25 ns spacing
R=0.5
(F. Zimmermann, 2005)
F. Ruggiero
CERN
calculation for 1 bunch train
heat load for quadrupoles higher in 2nd batch
LHC beam performance and luminosity upgrade scenarios
LHC arc heat load vs. spacing, Nb=1.15x1011
F. Ruggiero
CERN
(F. Zimmermann, 2005)
LHC beam performance and luminosity upgrade scenarios
Beam-Beam tune spread for round beams
tune shift from head-on
collisions (primary IP’s)
 HO
N b rp limit on HO

4 limits Nb/()
tune shift from long-range collisions
npar parasitic collisions around each IP
 LR  2n par
increases for closer
 HO
bunches or reduced
( dsep /  ) 2 crossing angle
s
 * relative beam-beam separation
 c
 c

 ( s)
 for full crossing angle c
d sep
HO / IP
no. of IP’s DQbb total
SPS
0.005
3
0.015
Tevatron (pbar)
0.01-0.02
2
0.02-0.04
RHIC
0.002
4
~0.008
LHC (nominal)
0.0034
3
~0.01
high-lumi in IP1 and IP5 (ATLAS
and CMS), halo collisions in IP2
(ALICE) and low-lumi in IP8 (LHC-b)
F. Ruggiero
CERN
conservative value for total
tune spread based on SPS
collider experience
LHC beam performance and luminosity upgrade scenarios
Beam-Beam tune footprints
Comparison of tune footprints, corresponding to betatron amplitudes
extending from 0 to 6  , for LHC nominal (red-dotted), ultimate (greendashed), and “large Piwinski parameter” configuration (blue-solid) with
alternating H-V crossing only in IP1 and IP5. (Courtesy H. Grote)
F. Ruggiero
CERN
LHC beam performance and luminosity upgrade scenarios
Proton beam lifetime versus
separation in RHIC
• SPS : t  5ms (d/)5 [measured 11/09/04]
• Tevatron: t ~ d3
[reported on 11/24/04]
• RHIC : t ~ d4 or d2 [measured 04/28/05]
F. Ruggiero
CERN
LHC beam performance and luminosity upgrade scenarios
RHIC Beam-Beam Long Range
compensation test: design – locations
F. Ruggiero
CERN
LHC beam performance and luminosity upgrade scenarios
LHC Upgrade: recent links & references
http://cern.ch/lhc-proj-IR-upgrade
LHC IR Upgrade collaboration meeting, CERN, 11-12 March 2002
http://care-hhh.web.cern.ch/care-hhh/
(web site of the CARE-HHH European Network on High Energy High
Intensity Hadron Beams)
http://care-hhh.web.cern.ch/CARE-HHH/LUMI-05/
CARE-HHH Workshop (LHC-LUMI-05) on “Scenarios for the LHC Luminosity
Upgrade”, Arcidosso, 30 Aug–3 Sept 2005
“LHC Luminosity and Energy Upgrade: A Feasibility Study”, O. Bruning, R.
Cappi, R. Garoby, O. Grobner, W. Herr, T. Linnecar, R. Ostojic,
K. Potter, L. Rossi, F. Ruggiero (editor), K. Schindl, L. Tavian, T. Taylor, E.
Tsesmelis, E. Weisse, and F. Zimmermann, CERN LHC Project Report 626
(December 2002)
“Parameters for First Physics and for 1033”, F. Ruggiero, in Proc. Workshop
on LHC Performance (Chamonix XII), Chamonix, 3–8 March 2003 (CERN
AB-2003-008 ADM, 2003), pp. 260–267
F. Ruggiero
CERN
LHC beam performance and luminosity upgrade scenarios