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Status of UA9

Status of UA9. Walter Scandale CERN EN-STI For the UA9 collaboration (CERN, INFN, IHEP, PNPI JINR, SLAC, LBNL, FNAL, Imperial College) CM14 27 April 2010. outlook. The beam and the layout Collimation efficiency With medipix With the LHC collimator scan simulations

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Status of UA9

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  1. Status of UA9 Walter Scandale CERN EN-STI For the UA9 collaboration (CERN, INFN, IHEP, PNPI JINR, SLAC, LBNL, FNAL, Imperial College) CM14 27 April 2010

  2. outlook • The beam and the layout • Collimation efficiency • With medipix • With the LHC collimator scan • simulations • Scan of the beam surrounding outside the collimation area • Reduction of nuclear rate in H8 • Summary of the results in 2009 • Plans for 2010 • Improved layout for 2010

  3. The SPS beam • Initial beam intensity: single bunch of a few 109 up to a few 1012. • Initial beam lifetime: larger than 80 h, determined by the SPS vacuum. • Lifetime with the crystal at 6s: 10 h (down to 15’ with the shaker on) • Halo flux in the crystal: a few 10 to a few 103 particles per SPS turn • Impact parameter (for 10 h lifetime) <ximpact> = 0.02 nm • Crystal critical angle qc=20 mrad (crystal angular acceptance ±2qc) Nominal beam parameters

  4. UA9 layout Not to scale

  5. Deflected beam QF518 QD519 QF520 Optimal offset positions along the beam line for α=150 μrad taratin

  6. Beam deflection based on channeling process 500 Amorphous orientation Amorphous orientation × 5 reduction rate Nuclear loss rate seen by a scintillator telescope downstream the crystal 1 counts Reflection range 100  Channeling peak Angle [mrad] -1800 -1700 -1600 -1500 • Nuclear loss rate (including diffractive) stronglydepressed • The loose mechanics of the goniometer induces a widened channeling peak

  7. Deflected beam profile with medipix Medipix sensor of the type inserted in the UA9 roman pot, provided by L. Tlustos (PH/ESE) • 256×256 square pixels • 1 pixel size = 55 mm • 1 frame integration time 1 s • Pick/valley density ratio = 10 • We observed a ratio of 30 (recording lost for a computer crash)

  8. Crystal 1 collimation efficiency using medipix No. of circulating (at t=0) - channeled particles (counted with Medipix) No. of circulating particle (BCT) Channeling though normal planes • Multi-pass channeling efficiency very large ->compatible with 100% • Measured efficiency ≥ 86 % • 20 % uncertainty due to BCT and MEDIPIX calibration (corrected with the data of the NA) • large CO glitches ≥ 200 mm every a few tenth of seconds during the data taking

  9. crystal channeling efficiency using the LHC-collimator

  10. crystal channeling efficiency using the LHC-collimator Channeling through skew planes of crystal 1 inducing a reduced efficiency

  11. Crystal channeling versus collimation efficiency Distribution of the impact parameter at the TAL • Simulation for crystal 2 • q0 = angle of the crystal respect to the beam envelope • q0 = 0 (perfect alignment) Pch=89% • q0 = 40 mrad Pch=75% • Measurements with crystal 2 • Channeling efficiency using the LHC collimator scan Pch=77.4% • Collimation efficiency measured with MEDIPIX and BCT Pcol=~100%

  12. MD 2009/9/22 Crystal 1 in channeling at ≈-1525 mrad. Closing LHC collimator at 07:20 The beam hitting the coll. increases The crystal is no longer the primary The TAL hits never go to zero (also due to the loss from the LHC coll). The LHC collimator hits the extracted beam The beam hitting the TAL decreases

  13. MD 2009/9/22 Crystal 1 in channeling at ≈-1525 mrad. Closing LHC collimator at 07:30

  14. MD 2009/11/4 Crystal 1 in channeling at ≈-1841 mrad. Closing LHC collimator at 17:20

  15. Halo detection by a TIDP scan TIDP Crystal 1 in channeling mode Beam loss count with the BLM 1.14 TAL Crystal 1 in amorphous mode 6s beam edge Halo region ≈ 2s TIDP 1.14 distance from the 6s beam edge • Collimation leakage hardly measurable –> inefficiency close to0 • Diffractive and betatronic loss rate negligible above 8s at the TIDP location • Loss in the region from 6 to 8 s compatible with the multiple scattering in the crystal

  16. nuclear rate in H8 • Nuclear loss rate (including diffractive) stronglydepressed • In channeling versus amorphous mode : × 5 in multi-turn (SPS) and × 3 in single-pass (NA) Loss rate in amorphous Loss rate in channeling amorphous orientation volume reflection channeling orientation simulation for channeling

  17. UA9 summary results of the 2009 MDs • Crystal collimation works very well based on channeling process • Optimal crystal alignment easily detected and achieved • Steady operation for many hours – even in presence of large CO changes (as in the very last MD) • Collimation leakage hardly measurable –> inefficiency compatible with 0 • Diffractive and betatronic loss rate negligible at the TIDP location (sextant 1, position 14) • About 20 % uncertainty due to BCT (Beam Current Transformer) and MEDIPIX calibration • Multi-pass channeling efficiency was measured • Clearance area between the deflected and the circulating beams as expected • Loss profile in the close-to-collimation area as expected from simulations • Nuclear loss rate (including diffractive) stronglydepressed • In channeling versus amorphous mode : × 5 in multi-turn (SPS) and × 3 in single-pass (NA) • Effect of the target length to be checked (crystal is a few mm long - LHC-collimator is 1 m)

  18. UA9 summary results of the 2009 MDs • Some points need clarifications • Not fully reproducible goniometer, • Crystal 1 in quasi-axial mode instead of planar mode • More instrumentation and collimators to observe far-from-collimation area • More stable accelerator requested • Channeling efficiency for vertical planes was 74% and 77% for Crystal 1 and 2 instead of about 90% according to simulation • Fluctuations of the channeling angles and widths and of the dechanneled fractions • The last two effects should be induced by an imperfect alignment of the crystals • New stable goniometers and slow angular scans should allow to obtain higher channeling efficiency

  19. Future plans and requests to the SPSC • Dedicated runs in the SPS and in the North Area also during 2010 • SPS: 5 full days of dedicated operation in storage mode at 120 GeV/c • North Area: 3 full weeks of dedicated operation in H8 with a micro-beam • Additional hardware installation in the SPS • The IHEP goniometer with two new crystals (to be installed this week) • Scintillators for the alignment of the new crystals (to be installed in Feb. ‘10) • New station in the dispersive area of the SPS after the crystal-collimation set (upstream of QF5-22) containing • Stopper (to be installed this week) • Cherencov in vacuum (to be installed this week) • Roman pot 2 with medipix (2 months of construction work yet needed) • The aim is to detect the collimation leakage and the diffractive events

  20. UA9 extended layout tank IHEP tank Not yet installed TAL (tungsten) 600x30x30 mm3 RP1 RP2 TAL2

  21. The IHEP goniometer Installed upstream of the RD22 tank It supports two new crystals Expected angular resolution 1 µrad

  22. The two new crystals Quasimosaic crystal supported by a large frame to avoid loss of large amplitude particles Strip crystal supported by a large bending frame to avoid loss of large amplitude particles

  23. The TAL2 in the dispersive area The TAL 2 is installed in the dispersive area of the missing magnet, just down stream of the TAL • It should intercept • halo not absorbed by the crystal collimation system • Diffractive particles produced in the crystal Aluminum scraper • The halo surrounding the circulating beam, which has messed the crystal collimation is detected • by the spray in a aluminum scraper • by a Cherenkov quartz • and later in 2010 by a medipix Quartz Cherenkov

  24. Final configuration of the TAL 2 The motor of the aluminum scraper Beam loss monitor scintillation telescope The quartz photomultiplier

  25. acknowledgments • The BE/OP-BI-RF and PH/ESE groups constantly supported our activity carefully preparing the SPS for our needs • Special personal thanks: • A. Taratin, S. Afanasyev for the nuclear loss measurements in the NA • C. Bracco, E. Laface, V. Previtali/CERN and S. Hasan, V. Ippolito, A. Mazzolari, D. Mirarchi/INFN for the huge effort in the data analysis • E. Metral, M.Silari for the perfect coordination of our efforts, plans and needs • R. Aymar for the approval of UA9 through the SPSC and the RB • S. Myers for approving and supporting the NA programme from 2006 to now • F. Ferroni, S. Bertolucci for the constant support through the CSN1 and NTA • CARE-HHH (2004-08) coordinators F. Ruggiero, W. Scandale and F. Zimmerman • INTAS programmes 132 (1999), 03-51-6155 (2003) and 05-96-7525 (2005) by which short bent crystals could be developed

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