Upload
eldora
View
66
Download
4
Tags:
Embed Size (px)
DESCRIPTION
Channeling collimation discussion issues. Dick Carrigan Fermilab 9th LARP Collaboration Meeting October 17 - 19, 2007 Stanford Linear Accelerator Center. Tevatron channeling projects. E853 – parasitic extraction done in mid nineties – originally in connection with SSC - PowerPoint PPT Presentation
Citation preview
Channeling collimation discussion issues
Dick Carrigan
Fermilab
9th LARP Collaboration Meeting
October 17 - 19, 2007Stanford Linear Accelerator Center
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
2
Tevatron channeling projectsE853 – parasitic extraction done in mid nineties –
originally in connection with SSCmost successful, maybe only successful SSC activity
Politics and operational challenges:funding, schedule, demise of SSCtunnel access
Technical challenges:alignment/goniometerhow to drive parasitic extraction – Peggs, …stability of loss monitors
Channeling collimation 2005 – presentations by Mokhov, Stilldirected toward LHCimportant successes – confirms RHIC, shows collimation
Operational challenge: running time
Technical challenges;alignment/goniometerstability of loss monitors
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
3
E853 Crystal Extraction at the Tevatron
see Carrigan, Mokhov, et al., Phys. Rev. ST Accel. Beams AB 1, 022801 (1998) http://prstab.aps.org/abstract/PRSTAB/v1/i2/e022801
Carrigan, Mokhov, et al., Phys. Rev. ST. Accel. Beams, AB 5, 043501 (2002)
http://prst-ab.aps.org/abstract/PRSTAB/v5/i4/e043501
(see these for collaborators)
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
4
E853 history and goalsHistory – In early 1990s, proposal for an SSC fixed target B flavor experiment. Crystal proposed for extraction. E853 given $100K to test at Tevatron. Used existing C0 dump – not needed at 900 GeV. A location with more dispersion would have helped longitudinal noise excitation
Goals•Extract 106 protons/s with 1012 circulating•Study extraction efficiency•Show luminosity lifetime not affected•Investigate background at CDF and D0
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
5
E853 Successes
•Extracted significant beams from the Tevatron
parasitic, kicked and RF stimulated•First ever luminosity-driven extraction•Highest energy channeling ever (until recent
Tevatron collimation studies)•Useful collimation studies•Extensive information on
time-dependent behavior•Very robust
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
6
First crystal extraction at the Tevatron C0 straight section June 6, 1995 (kick mode)
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
7
E853 ExperienceBad:• Interaction counters very sensitive to beam motion <background?>• “Extracted” beams in the 108 - 109 regime need special instrumentation• Beam halo behavior is often non-linear• Lattice location important (RHIC – difficult, Tevatron extraction, collimation
better but imperfect)
Good:• Crystal extraction works well, robust• Extraction in diffusion modes means crystal collimation can work• Multiple pass works, can take bigger goniometer steps
Neutral:• Large variety of time dependent behavior
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
8
Channeling collimation studies at the
Fermilab Tevatron
Dean Still, Jerry Anala, Todd Johnson, Robert Reilly, Dwayne Plant, Dick
Carrigan, Sasha Drozhdin, Ray Fliller,
Nikolai Mokhov, and Vladimir Shiltzev
Fermilab
9
Crystal Angle vs displacement at E03H
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-10 -8 -6 -4 -2 0
E03H collimator position (mm)
Lo
ss o
n L
E03
3 (v
olt
s)
118 urad
343 urad
520 urad
806 urad
238 urad
out
Crystal Angle vs displacement at E03H
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-10 -8 -6 -4 -2 0
E03H collimator position (mm)
Lo
ss o
n L
E03
3 (v
olt
s)
118 urad
343 urad
520 urad
806 urad
238 urad
out
Collimator scans for different crystal angles-Mokhov
ChannelChannel
ReflectionsReflections
ScatterScatter•Channeled beam produces a shoulder 7 + 0.8 mm from the coreChanneled beam produces a shoulder 7 + 0.8 mm from the core•The channeled beam should have been ~10.5 mm from the core.The channeled beam should have been ~10.5 mm from the core.•First data set suggested the channeled beam was hitting an aperture.First data set suggested the channeled beam was hitting an aperture.•But on 1/10/2006, after moving the crystal 10mm, new data proved there But on 1/10/2006, after moving the crystal 10mm, new data proved there was no aperture limit. was no aperture limit. Measured deflection ~ 325 Measured deflection ~ 325 μμrad, not 440 rad, not 440 μμradrad..
Beam probe w/out crystal
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
10
E03 data fitted and differentiated
Channeling peak is > 50% of deflected beam. Remainder dechanneling? Sigma is twice critical angle, some due to beam divergence.
0
0.5
1
1.5
2
2.5
3
3.5
-10 -8 -6 -4 -2 0 2
EO3H (mm)
LE
033
yie
ld
500 400 300 200angle (μrad)
100
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
11
Comments for the discussion paper
• Instrumentation
• Studies/Experiment
• Simulation/theory needs
Radiation damage for some other time
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
12
Instrumentation• What does single particle instrumentation
mean?
• Need for Roman pots
• Reducing “background” in the BLMs. What is “background?”
• Reducing fluctuations
• Goniometer – need for redundancy, linearity, angular range, …,
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
13
Studies/Experiment
• What is experiment plan (see draft of “Discussion Document”)
O shaped vs strip crystal• Strengthening the collimation results• Speeding up measurements, particularly
alignment• Should experiment also mirror LHC needs?• Fundamental aligned crystal questions
for example - demonstrate that whole arc processes (volume reflection) kicks in opposite direction from channeled
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
14
Simulation/theory needs
• What simulation is needed of alignment curves with crystal bend, length
• Simulation of collimator withdrawal curves
• Simple parameterization of bend, crystal length
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
15
Comments?
D. CarriganLARP CM9 Oct. 17-19,2007 SLAC
16
For more accelerator channeling information see:
Fermilab - Dean Still’s site:http://www-bdnew.fnal.gov/tevatron/projects/crystal_collimator/index.htm
Fermilab channeling home:http://home.fnal.gov/~carrigan/Channeling/Channeling_master.htm
Fermilab - Channeling Formulary: http://home.fnal.gov/~carrigan/Channeling/Channeling_formulary.htm
Other sites
CERN:
http://www.fe.infn.it/%7Efiorini/
Serpukhov:
http://crystalbeam.narod.ru/