Channeling collimation discussion issues

16
Channeling collimation discussion issues Dick Carrigan Fermilab 9th LARP Collaboration Meeting October 17 - 19, 2007 Stanford Linear Accelerator Center

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

Transcript of Channeling collimation discussion issues

Page 1: Channeling collimation discussion issues

Channeling collimation discussion issues

Dick Carrigan

Fermilab

9th LARP Collaboration Meeting

October 17 - 19, 2007Stanford Linear Accelerator Center

Page 2: Channeling collimation discussion issues

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

Page 3: Channeling collimation discussion issues

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)

Page 4: Channeling collimation discussion issues

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

Page 5: Channeling collimation discussion issues

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

Page 6: Channeling collimation discussion issues

D. CarriganLARP CM9 Oct. 17-19,2007 SLAC

6

First crystal extraction at the Tevatron C0 straight section June 6, 1995 (kick mode)

Page 7: Channeling collimation discussion issues

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

Page 8: Channeling collimation discussion issues

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

Page 9: Channeling collimation discussion issues

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

Page 10: Channeling collimation discussion issues

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

Page 11: Channeling collimation discussion issues

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

Page 12: Channeling collimation discussion issues

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, …,

Page 13: Channeling collimation discussion issues

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

Page 14: Channeling collimation discussion issues

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

Page 15: Channeling collimation discussion issues

D. CarriganLARP CM9 Oct. 17-19,2007 SLAC

15

Comments?

Page 16: Channeling collimation discussion issues

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/