1. CRYSTALS AS LONG-TERM IMPROVEMENT FOR LHC COLLIMATION
Walter Scandale, Nikolai Mokhov
Conceptual Design Review
LHC Phase II Collimation
CERN, Switzerland
April 2-3, 2009

2. Outlook The crystal collimation concept The UA9 experiment
Plans for UA9
Conclusions for UA9
Results and Plans for FNAL

3. Two stage collimation in a circular collider How it works ? Beam Core
Secondary halo p e
Primary collimator
(scatterer)
Beam Core
Shower
Primary
halo (p)
Secondary collimator
(massive absorber)
How it works ?
Short scatterer deflects the primary halo (ap. r1=N1√βTWISSε)
Long collimator intercepts the secondary halo (ap. r2=N2√βTWISSε)
halo particles captured through amplitude increase via multiple scattering and multi-turn effect. r1 r2
<x’2>~ L

4. Crystal collimation Beam Core Primary halo (p) Crystal p
E. Tsyganov & A. Taratin (1991)
Beam propagation
Beam Core
Crystal channeling
Primary
halo (p)
Crystal p
Absorber
Coherent deviation of the primary halo
Larger collimation efficiency
Reduced tertiary halo
Past attempts in IHEP and RHIC
On-going tests at CERN and FNAL

5. The underground experiment in the SPS
UA9
The underground experiment in the SPS
Approved by the CERN Research Board of the 3 Sept 2008
Goals:
Demonstrate loss localization
Measure channeling and collimation efficiency
Measure the single particle dynamics
CERN
INF N
PNPI
IHEP
JINR
SLAC
FNAL
LBNL
TAL

6. UA9 layout
tank
IHEP
tank
RP1
RP2
TAL (tungsten)
600x30x30 mm3

7. RD22 tank with goniometers and thin target

8. crystals

9. Laser table for crystal alignment
Layout of the RD22 tank
Laser table for crystal alignment
Scintillating counter
Scintillating counter
GEM
GEM
Beam axis
Crystal
Multi
cables
Single
strip
crystal
scraper
Horiz.
1mm W
30x30 mm2
Crystal
Multi
cables
Cerencov
Quartz
detector
Quasi
mosaic
crystal
Crystal
Multi
cables

10. TAL (secondary collimator)

11. RP1 (the CERN roman pot)
RP2

12. Beam loss and scintillator counters
BLM
BLM
BLM
BLM C3 C4

13. Expected efficiency for α=150 rad
position
angle
TAL hit
amorphous orientation
Optimal orientation for channeling
VR (-)

14. Conclusion UA9 ready to start crystal collimation tests in June 09
Infrastructure ready (cables, mechanics, beam loss monitors, RF noise, Beam intensity monitors)
Basic hardware installed (Tank, two gonioneters, two crystals, TAL)
Detectors in progress
Already installed: 1 cerencov, 6 scintillators, 3 GEM, 1 si-strip, 3 BLM
To be installed possibly in May: 1 cerencov, 2 scintillators, a fibrometer, more si-strips
UA9 ready to start crystal collimation tests in June 09

15. T980 at Tevatron: Mission
Develop a collimation system for hadron colliders based on channeling crystal techniques, which has a promise to reduce machine impedance, beam losses in superconducting magnets, improve background conditions in the collider detectors and be compatible with heavy-ion operation.
Start routine use of crystal collimation in the entire Tevatron collider store.
Study the system’s performance and underlying beam dynamics exploiting the unique possibility provided by the Tevatron collider to evaluate an engineering implementation of this technique in the LHC.

16. E0 Crystal Collimation Layout
T980 at Tevatron: the layout
E0 Crystal Collimation Layout m m
crystal
E03H
Collimator
3.5 mm
channeled beam m
Pin Diode
LE033 BLM
Flying
Wire
Channeled beam
At E03H

17. E0 CRYSTAL COLLIMATION COMPONENTS
“Successful” 0.44mrad O-shaped
crystal of studies
“Unsuccessful” 0.15mrad strip
crystal of 2007 studies
Laser – angular
measurement
5mm
Beam Direction
PIN Diode
BLM
BLM
Pin Diode
E03 Secondary
Collimator
E0 Crystal Collimator Assembly

18. T980 End-of-Store Studies18

19. A factor of >5 lower irradiation of downstream components
COMPARING EFFECTS OF PROTON HALO LOSSES FOR BENT CRYSTAL AND TUNGSTEN TARGET
Crystal aligned at peak (118 mrad)
CDF
E03 BLM
PIN
Using the crystal:
The secondary collimator can remain further (1 mm or so) from the beam thus reducing impedance.
Almost a factor of 2 reduction of CDF losses (in agreement with modeling)!
A factor of >5 lower irradiation of downstream components

20. First Use of Crystal for the Entire Collider Store
Successful test of crystal automatic insertion with no impact on the store.
Evidence of better cleaning.
Found angular drift over the entire store (heating?)
Tests will continue in ‘09 and ’10 with new crystals and and additional goniometer