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

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

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

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

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

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

RD22 tank with goniometers and thin target

crystals

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

TAL (secondary collimator)

RP1 (the CERN roman pot) RP2

Beam loss and scintillator counters BLM BLM BLM BLM C3 C4

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

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

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.

E0 Crystal Collimation Layout T980 at Tevatron: the layout E0 Crystal Collimation Layout 23.731 m 33.115 m crystal E03H Collimator 3.5 mm channeled beam 23.731 m Pin Diode LE033 BLM Flying Wire Channeled beam At E03H

E0 CRYSTAL COLLIMATION COMPONENTS “Successful” 0.44mrad O-shaped crystal of 2005-2006 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

T980 End-of-Store Studies 18

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

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