Transcript US-LHC Activities in AD Tanaji Sen

US-LHC Activities in AD
Tanaji Sen
Overview
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The LHC
US-LHC Construction Project
US-LARP Goals and Activities
Accelerator Physics
Instrumentation
Beam Commissioning
LHC@FNAL
The wise speak only of what they know
Gandalf, Lord of the Rings
LHC
Control Room
Key Parameters
Tevatron
Injection Energy
150 GeV
Top Energy
980 GeV
Particles/bunch
2.7 x 1011
# of bunches
36
Trans. Emitt(95%)
20 mm-mrad
Beam current (p)
0.074 A
Stored energy/beam 1.5 MJ
Peak Luminosity
1.7 x 1032
LHC
450 GeV
7000 GeV
1.15 x 1011
2808
22.5 mm-mrad
0.584 A
362 MJ
1 x 1034
US-LHC Construction Project
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Interaction Region Quads (FNAL)
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Interaction Region Dipoles (BNL)
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Interaction Region Cryogenic Feedboxes (LBL)
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Interaction Region Absorbers (LBL)
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Accelerator Physics (FNAL, BNL, LBL)
- related to IR designs and magnets
- ecloud, noise effects
Last magnets to be delivered in 2006
LHC IR Quads at FNAL
FNAL quads
MBXA
DFBX
“D1”
BNL
C
O
R
R
MQXA
C
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R
R
T
A
S
MQXB
“Q3”
LBNL
CERN
C
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R
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MQXB
“Q2”
KEK
C
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MQXA
R
To IP
“Q1”
FNAL
1st IR quad ready for
shipment in May 2004
 FNAL is delivering 18
IR quads to the LHC
 All IR quads
(FNAL, KEK) are
cryostatted at FNAL
and shipped from here
 Last quad to be
shipped in late 2006.
FNAL quads installed in IR8
Mission Accomplished ?
Courtesy: J. Kerby
US- LARP
Goals – stated by J. Strait (2002)
 Extend and improve the performance of the LHC so
as to maximize its scientific output in support of
US-CMS and US-ATLAS
 Maintain and develop the US labs capabilities so
that the US can be the leader in the next
generation of hadron colliders.
 Serve as a vehicle for US accelerator physicists to
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pursue their research
Train future generations of accelerator physicists.
It is the next step in international cooperation on
large accelerators.
Fermilab has been appointed the “Host Laboratory” to
lead this program.
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US LARP Institutions
Two main areas:
 High field magnets
 Accelerator systems
Accelerator Physics, Instrumentation,
Collimation, Commissioning (beam &
hardware)
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High field magnets: BNL, FNAL, LBL
Accelerator Physics: BNL, FNAL, LBL
Instrumentation: BNL, FNAL, LBL, UT Austin
Collimation: SLAC
Commissioning: BNL, FNAL, LBL
US-LARP Goals
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Accelerator Physics and Experiments
- understand performance limitations of current IRs and
develop new designs
- Beam dynamics calculations and related experiments
Develop high performance magnets for new higher
luminosity IRs
- large-aperture, high gradient quadrupoles using Nb3Sn
- high field beam separation dipoles and strong correctors
Develop advanced beam diagnostics and
instrumentation
- luminosity monitor, tune feedback, Schottky monitor,
rotatable collimators
- other systems as needed for improving LHC performance
Commissioning
- participate in the sector test and LHC beam commissioning
- commission hardware delivered by the US
IR Upgrade
Luminosity and IR upgrade
J. Strait
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L
I .F ( )
4 *  N
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A luminosity upgrade will be required
around ~2015 to keep the LHC physics
program productive.
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An IR upgrade is a
straightforward way to
increase the luminosity
– by a factor of 2-3
It must also deal with
higher beam currents
and 10 times larger
debris power at
L=1035cm-2s-1
Several optics design
issues
~50% of LARP effort is
in IR magnet design
Quadrupoles 1st option
Advantages
 Allows smaller β*, minimizes
aberrations.
 Lower accumulation of charged
particle debris from the IP.
 Operational experience from
the first years of running.
Disadvantages
 More parasitic beam-beam
interactions.
 Crossing angle has to increase
as 1/√β*
 IR correction systems act on
both beams simultaneously
Baseline Design
Dipoles 1st – 2 options
Advantages
 Fewer parasitic interactions.
 Correction systems act on single
beams.
 No feed-down effects in the
quads
Triplets
Doublets
Disadvantages
 Large energy deposition in the
dipoles.
 Beta functions are larger →
increases aberrations.
 Longer R&D time for dipoles
 Longer commissioning time
after the upgrade.
Optics Solutions
βMax = 9 km
Quads first
LARP magnet program aims to build 15T pole tip fields
βMax = 27 km
Dipoles first: triplets
βMax = 25 km
Dipoles first: doublets
J. Johnstone, TS
IR Design Issues
→ Luminosity Reach
 Requirements on magnet fields and apertures
 Optically matched designs at all stages
 Energy deposition
 Beam-beam interactions
 Chromaticity and non-linear correctors, field quality
 Dispersion correction
 Susceptibility to noise, misalignment, ground motion;
emittance growth
 Closest approach of magnets to the IP (L*)
 Impact of Nb3Sn magnets, e.g flux jumps
 R&D time required to develop the most critical
hardware and to integrate it in the LHC
….. All need to be considered in defining the luminosity
reach
Towards a Reference Baseline Design
Proposal by F. Ruggiero (CERN)
 “Define a Baseline, i.e. a forward looking
configuration which we are reasonably confident
can achieve the required LHC luminosity
performance and can be used to give an accurate
cost estimate by mid-end 2006 in a Reference
Design Report
 Identify Alternative Configurations
 Identify R&D to
- support the baseline
- develop the alternatives”
Separately, the LARP magnet program has been tasked to
deliver a working prototype of a Nb3Sn quadrupole by 2009.
Wire Compensation of
beam-beam interactions
Long-range interactions
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Long-range beam-beam
interactions are expected
to affect LHC
performance – based on
Tevatron observations
and LHC simulations
Wire compensator is
proposed to mitigate their
impact
RHIC has a 2 ring layout
like the LHC – can be
used to test the principle
Difference in kicks between a round beam
and a wire < 1% beyond 3 sigma
Wire compensation in RHIC and LHC
RHIC
IP6
Location of wire compensators
Installation in Summer 2006
LHC
IP
Reserved for wire compensators
To be installed if required to improve
performance.
Feasibility would determine upgrade path
RHIC beam-beam experiments
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Motivation for experiments: Test of wire compensation
in 2007
Determine if a single parasitic causes beam losses that
need to be compensated
Experiments in 2005 and 2006
Remote participation at FNAL via logbook
Motivation for simulations: Tests and improvements of
codes, predictions of observations in 2006 and of wire
compensation
Several groups: FNAL, SLAC, LBL, University of Kansas
(coordinated at FNAL)
Website: http://www-ap.fnal.gov/~tsen/RHIC
Beam-beam Experiments and
Simulations (2006)
FNAL Simulations
 Beam lifetime responds to vertical
separation but vertical separation 
4σ (1st study – April 5th, 2006)
 4 studies in all (April-May) to
explore larger separations and tune
space
 Analysis to find dependence on
beam separation in progress
Simulated lifetimes
show a linear
dependence on the
beam separation
V. Ranjbar, TS
Wire Compensator in RHIC
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1 unit in each
ring
2.5m long
Currents
between 3.8 –
50 A
Vertically
movable over
65mm
Install in
Summer 2006
Pulsed Wires
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LHC bunch pattern
Pulse pattern
Required for bunch to
bunch compensation –
PACMAN bunches
Challenges are the
high pulse rate and
turn to turn stability
tolerances
Strength
Pulse rate
120 A-m
439 kHz
Turn to turn
amplitude
stability
10-4
Turn to turn
timing stability
0.04 nsec
Open Design Challenge
Energy Deposition
Energy deposition
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Primary source of radiation in the IR magnets: pp
collisions, ~ Luminosity
Tevatron: debris power ~ 2 W
LHC at 1035cm-2s-1, debris power ~ 9kW
Energy deposition is viewed as the major constraint
on the IR upgrade
Could be key in deciding between quads first or
dipoles first.
Other sources include operational beam losses (e.g.
beam gas scattering) and accidental losses (e.g.
misfiring of abort kickers)
Energy Deposition Issues & Constraints
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Quench stability→ Peak power density
Require Epeak to be below the quench limit by a factor of 3
Magnet lifetime → peak radiation dose and lifetime limits for
various materials
Baseline LHC: expect lifetime ~ 7 years for IR magnets
Upgrade LHC: requires new radiation hard materials
Dynamic heat loads → Power dissipation and cryogenic
implications
Require heat load < 10 W/m
Residual dose rates → hands on maintenance
Require residual dose rates < 0.1 mSv/hr
Dedicated system of charged particle and neutral absorbers in
the IRs
Energy Deposition: Open Mid-plane Dipole
 ED issues constrain the
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R. Gupta (BNL)
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dipole design to have no
coils in the mid-plane
Εpeak in SC coils
~0.4mW/g, below the
quench limit
Estimated lifetime based
on displacements per
atom is ~10 years
Dipole design will require
significant R&D, further
LARP design work
postponed
N. Mokhov
Quadrupole first design
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Without mitigation,
Epeak > 4 mW/g.
Target value is
~1.7mW/g
Mitigation by thick
inner liner
Stainless steel liners
are not adequate
Thick TungstenRhenium liner
reduces
Epeak ~ 1.2 mW/g
I. Rakhno
Tertiary Collimators
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Designed to protect the detector and
IR components from operational and
accidental beam losses
Similar collimator used at A48
in the Tevatron to protect
against abort kicker misfire
For the LHC propose 1m long
Tungsten or Copper collimator
upstream of neutral absorber
To IP
N. Mokhov
LHC Injector
LHC Injector in the LHC tunnel
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Injector will accelerate beams from 0.45TeV to
~1.5TeV
- Field quality of LHC better at 1.5GeV
- Space charge effects lower, may allow
higher intensity bunches
- Could allow easier transition to LHC doubler
The injector will be installed in the LHC tunnel
during scheduled LHC shutdowns
Return to the standard SPS injection into the LHC
will be possible
The main magnets will be the type of super-ferric
combined function magnets proposed for the VLHC
I.
H. Piekarz (TD)
LHC Injector (LER)
Vertical distance between LER and LHC
beams is 1.35m
VLHC low-field magnet
0.6 T (injection) → 1.6 T
Beam Transfer
Sequence: SPS-> Injector -> LHC
--- what is not surrounded by
uncertainty cannot be the truth
R.P. Feynman
Fast pulsing magnets (PM) have
to be turned off within 3 microsecs after LHC is filled.
CERN Workshop October 2006
Instrumentation
 Schottky Monitor
 Tune and Chromaticity Feedback
 New Initiatives
Schottky Monitor at the Tevatron
Allows measurements of:
 Tunes from peak
positions
 Momentum spread from
average width
 Beam-beam tune spread
of pbars
 Chromaticity from
differential width
 Emittance from average
band power
Schottky Monitor Design
R. Pasquinelli, A. Jansson
Schottky Monitor will provide
unique capabilities
– Only tune
measurement during
the store
– Bunch-by-bunch
measurement of
parameters such as
Tune, Chromaticity
– Average measurements
as well
– Momentum spread &
emittance
 Non invasive Technique
 Diagnosis of beam-beam
effects and electron cloud
4 Monitors to be installed in the LHC, Summer 2006
Tune and Chromaticity feedback
Goals
 Control the tune during the
acceleration ramp to avoid
beam loss
 Control the chromaticity during
the snapback at start of ramp
 PLL method: excite the beam
close to the tune and observe
the resonant beam transfer
function
 Then used in a feedback
system to regulate the
quadrupole current and tune
Measurement in RHIC with tune
feedback – tune changes ~ 0.001
Tune & chromaticity at the Tevatron
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The Direct Diode Detection
method (3D BBQ) from CERN
implemented in the Tevatron –
complements tune
measurements from the
Schottky monitors. More
sensitive than the Schottky.
This 3D BBQ has been used to
measure the chromaticity with
a method due to D. McGinnis.
Interest in implementing this
method at RHIC and the SPS
C.Y. Tan
Phase Modulation Off
Phase Modulation On
New FNAL Initiatives - proposed
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AC Dipole (A. Jansson)
Electron lens compensation of head-on
interactions (V. Shiltsev)
Crystal collimation (N. Mokhov)
Measure field fluctuations in magnets
(V. Shiltsev)
Commissioning
 LHC Plans
 LARP involvement
 LHC@FNAL
LHC Commissioning Plan
Stage I
No beam
Beam
II
III
IV
Beam
I. Pilot physics run
First collisions
43 bunches, no crossing angle, no squeeze, moderate intensities
Push performance (156 bunches, partial squeeze in 1 and 5, push
intensity)
Performance limit 1032 cm-2 s-1 (event pileup)
II. 75ns operation
Establish multi-bunch operation, moderate intensities
Relaxed machine parameters (squeeze and crossing angle)
Push squeeze and crossing angle
Performance limit 1033 cm-2 s-1 (event pileup)
III. 25ns operation I
Nominal crossing angle
R. Bailey (CERN)
Push squeeze
Increase intensity to 50% nominal Performance limit 2 1033 cm-2 s-1
IV. 25ns operation II
Push towards nominal performance
Beam Instrumentation – R.Garoby, R.Jones
Activity
Responsible
Other CERN
Screens
E.Bravin
A.Guerrero
H.Burkhardt (AP)
G.Arduini (AP)
BCT
P.Odier
D.Belohrad
M.Ludwig
H.Burkhardt (AP)
J.Jowett (AP)
BPM and orbit
R.Jones
L.Jensen
J.Wenninger (OP)
W.Herr (AP)
I.Papaphilippou (AP)
BLM
B.Dehning
E.Holzer
S.Jackson
R.Assmann (AP)
H.Burkhardt (AP)
B.Jeanneret (AP)
S.Gilardoni (AP)
PLL for Q, Q’, C
R.Jones
M.Gasior
P.Karlsson
S.Fartoukh (AP)
O.Berrig (AP)
J.Wenninger (OP)
X
Profile monitors
S.Hutchins
J.Koopman
A.Guerrero
H.Burkhardt (AP)
S.Gilardoni (AP)
M.Giovannozzi (AP)
X
Schottky monitors
F.Caspers (RF)
R.Jones
S.Bart-Pedersen
E.Metral (AP)
C.Carli (AP)
F.Zimmermann (AP)
X
Luminosity monitors
E.Bravin
S.Bart-Pedersen
R.Assmann (AP)
F.Zimmermann (AP)
X
LARP
Expression of Interest Form
In anticipation of LHCrelated studies using the
SPS in the coming months
and commissioning next
year, LARP is soliciting
interest for involvement in
same.
http://larp.fnal.gov/comm
issioningForm.html
is the link for you to
register your interest in
being part of this effort.
Please respond to Elvin Harms by June 1st
SPS studies – test LHC issues
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LHC collimator tests
LSS6 commissioning
TI8 extraction test
LSS4/LSS6 interleaved
LHC beam lifetime
LHC orbit feedback
BBLR – beam-beam compensation
LHC BLM tests in the PSB
--- sample of studies planned
From G. Arduini (CERN)
LARP plans for Beam Commissioning
 Refining areas of involvement, identifying CERN
counterparts
~15 people signed up (across all 4 labs)
 LARP presence during SPS run in Summer ’06
3 FNAL people participating, room for a few more
 Sector test presence planned
About 2 weeks, late 2006 – early 2007
 Software effort
In support of instruments and control room here
 Planning for long-term visits during LHC commissioning
E. Harms
What is LHC@FNAL?
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A Place
• That provides access to information in a manner that is similar to what is
available in control rooms at CERN
• Where members of the LHC community can participate remotely in CMS
and LHC activities
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A Communications Conduit
• Between CERN and members of the LHC community located in North
America
• LARP use: Training before visiting CERN, Participating in
Machine Studies, Analysis of performance, “Service after the
Sale” of US deliverables
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An Outreach tool
• Visitors will be able to see current LHC activities
• Visitors will be able to see how future international projects in particle
physics can benefit from active participation in projects at remote
locations.
E. Gottschalk
Planned Opening in September 2006
LHC@FNAL
You can observe a lot just by
watching
Yogi Berra
Control Room at CERN
13 operators on shift + experts
Started operation on Feb 1, 2006
LHC Challenges
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Machine protection
Quench protection e.g at 7 TeV, fast losses
< 0.0005% bunch intensity
Collimation (400 degrees of freedom!)
Controlling 2808 bunches
Snapback and ramp
ΔQ’ (snapback) ~ 90,
ΔQ’ (ramp & squeeze) ~ 320
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Summary of LARP activities
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Optics design of IR upgrade
Energy deposition calculations in IR magnets
Design of tertiary collimators
Beam-beam and wire compensation experiments
Optics design of a proposed LHC injector
Design of Schottky Monitor
Tests of tune and chromaticity tracking
Proposed new initiatives: AC dipole, E-lens, Crystal
collimation, Field fluctuations
Participation in SPS and LHC sector tests
LHC beam commissioning
LHC@FNAL
Web pages
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AD: larp.fnal.gov
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US-LARP: dms.uslarp.org
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E. McCrory
LARP document database
larpdocs.fnal.gov
FNAL-TD, BNL, LBL, SLAC also have web
pages – links from the uslarp page
Credits
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Accelerator Physics: J. Johnstone, N.
Mokhov, I. Rakhno, V. Ranjbar
Instrumentation: A. Jansson, R.
Pasquinelli, V. Shiltsev, C.Y. Tan
Commissioning: E. Harms, E. McCrory,
J. Slaughter, M. Syphers
Backups
US-LARP activities in 2006
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Accelerator Physics
FNAL: IR design, Beam-beam compensation, Energy
deposition, tertiary collimators
BNL: Beam-beam compensation
LBL: Electron cloud
Instrumentation
FNAL: Schottky monitor, tune feedback
BNL: Tune feedback
LBL: Luminosity monitor
Rotating collimators – SLAC
Magnets
High field quads: FNAL, BNL, LBL
Commissioning – all labs
Features of Doublet Optics
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Symmetric about IP from Q1 to Q3, anti-symmetric from
Q4 onwards
Q1, Q2 are identical quads, Q1T is a trim quad (125
T/m). L(Q1) = L(Q2) = 6.6 m
Q3 to Q6 are at positions different from baseline optics
All gradients under 205 T/m
At collision, β*x= 0.462m, β*y = 0.135m, β*eff= 0.25m
Same separation in units of beam size with a smaller
crossing angle ΦE = √(β*R/ β*E) ΦR = 0.74 ΦR
Luminosity gain compared to round beams
Including the hourglass factor,
LHC Commissioning Plan
From R. Bailey (CERN)
Where are we ?
1 Injection and First turn
Overall strategy OK
Stage I
43 bunches
Stage II
75ns
Stage III 25ns low I
Stage IV
25ns high I
3 450 GeV: initial commissioning
Stage I looked at
7 Snapback – single beam
Some details behind
Need to make this into a detailed commissioning
plan
Best developed by the people who will
implement it
Machine
coordinators/Commissioners/EICs +
Accelerator Systems
Work through 2006 (suggest 20% activity)
2 Circulating beam, RF capture
4
450 GeV: detailed
measurements
5 450 GeV: 2 beams
6 Nominal cycle
8 Ramp – single beam
9 Single beam at physics energy
1
Two beams to physics energy
0
1
Physics
1
1
Commission squeeze
2
1
Physics partially squeezed
3
Machine protection
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Metal damage
450 GeV: 50 nominal bunches
7 TeV: 7 x 109, about 6% of 1 bunch
Quench protection
Fast losses 450 GeV: 109, 7TeV: 5x105
During abort 450GeV: 1.4x109 p/m in gap
7TeV: 2x106 p/m in gap
Collimator damage
Fast losses 450 GeV: 260 bunches
7 TeV: 4 bunches
LHC Sector test with beam
3.3 km of the LHC including one
experiment insertion and a full arc
LHC@FNAL