“BTF Test of Cherenkov detector for proton Flux Measurement ( CpFM )”

1. “BTF Test of Cherenkov detector for proton Flux Measurement (CpFM)” First BTF Users Workshop 6-7 May 2014 - Laboratori Nazionali di Frascati Marco Garattini on behalf of the UA9 Cherenkov detector team 3 M. Garattini, 1 D. Breton, 1 V. Chaumat, 3 G. Cavoto, 1 S. Conforti Di Lorenzo, 1 L. Burmistrov, 3 F. Iacoangeli, 1 J. Jeglot, 2 F. Loprete, 1 J. Maalmi, 2 S. Montesano, 1 V. Puill, 2 W. Scandale, 1 A. Stocchi, 1 J-F Vagnucci 1LAL, UnivParis-Sud, CNRS/IN2P3, Orsay, France 2 CERN - European Organization for Nuclear Research, CH-1211 Geneva 23, Switzerland 3 INFN - Roma La Sapienza, Italy

2. Outline • UA9 experiment at SPS • LUA9 project • CpFM detection chaincomponents • Opticalsimulations on the Cherenkovradiator • Beam tests at BTF of simplified prototypes (October 2013) • Beam test at BTF of the CpFM full chain (April 2014) • First preliminary results of the beam test • Conclusions

3. Crystal assisted collimation • Bent crystals work as a “smart deflectors” on primary halo particles • Coherent particle-crystal interactions impart large deflection angle that minimize the escaping particle rate and improve the collimation efficiency θch≅ αbending amorphous channeling R. W. Assmann, S. Redaelli, W. Scandale, “Optics study for a possible crystal-based collimation system for the LHC”, EPAC 06c <θ>MCS≅3.6μrad @ 7 TeV θoptimal @7TeV≅ 40 μrad beam core primary halo 6 6.2 Multiple Coulomb scattered halo (multi-turn halo) 7 Dechanneled particles in the crystal volume 10 Deflected halo beam Normalizes aperture [σ] secondary halo & showers >10 Silicon bent crystal Sensitive devices (ARC, IR QUADS..) absorber 1m W primary collimator 0.6 m CFC secondary collimator 1m CFC masks secondary collimator 1m CFC Absorber retracted Collimators partially retracted

4. LUA9 projectUse bent crystal at LHC as a primary collimator LHC beam pipe (primary vacuum) To monitor the secondary beam a Cherenkov detector, based on quartz radiator, can be used. Aim: count the number of protons with a precision of about 5% (in case of 100 incoming protons) in the LHC environment. • Main constrains for such device: • - No degassing materials (inside the primary vacuum). • - Radiation hardness of the detection chain (very hostile radioactive environment). • - Compact radiator inside the beam pipe (small place available) • Readout electronics at 300 m • Cherenkov detector for proton Flux Measurements (CpFM)

5. CpFM detection chaincomponents Radiation hard quartz(FusedSilica) radiator The flange with view port attached to the movablebellow The light will propagate inside the radiator and will then be transmitted to the PMT via a bundle of optical fibers • Quartz/quartz (core/cladding) radiation hard fibers. • 300 m cable • USB-WC electronics. For more details see : • USING ULTRA FAST ANALOG MEMORIES FOR FAST PHOTO-DETECTOR READOUT(D. Breton et al. PhotoDet 2012, LAL Orsay)

6. Geant 4 OpticalSimulation Differentreflectioncoefficient Angle wrtthe fiberaxis At the end of the bar At the end of the CpFMchain

7. BTF Setup (October 2013) LAL Cerenkov INFN Cerenkov e- Beam BTF Remote ControlTable BTF Calorimeter

8. Radiatorwithfibers bundle Charge signal normalized to number of incident electron and electron path length in the radiator (arbitrary units) - 47º The widthof the peakiscompatiblewith the numerical aperture of the fibers Opticalgreaseat interfacesbetweenfibers, PMT and radiator Radiator rotation angle

9. Best configurationforCpFM Beam Fibers Quartz Flange brazedconfiguration Viewport configuration ̴ 43˚ • L bar • or • I bar The “double bar” configurationwillbeusefultomeasure the diffusionof the beam and the background

10. Geant 4 OpticalSimulation Differentreflectioncoefficient Angle wrtthe fiberaxis

11. New BTF Set-up ofCpFM (April 2014) Cherenkovbars 47º end of the bars MCP-PMT Fibers bundle PMTsblackboxes Fibers bundle

12. 1.CpFM alignment with the beam: X-Y scan Measurement in the range 50, 100, 300, 400, 500 e- for “I”, “L” bars: 2.Quartz + MCP-PMT : to check that we have a signal at the quartz output even with the curved shape and the interface with the false flange… 3.The CpFM: quartz + fibers bundle + PMTs + long low attenuation cables + WaveCatcher 4. Quartz + Viewport (or stack of glass plates) + MCP-PMT : to simulate an inclined viewport with different thickness 5. Bundle of fibers inside the beam: the background due to the bundle itself 6. Cross-talk between the 2 channels of the CpFM 7. Quartz + metallic rings of different widths to simulate the brazing thickness Measurementwith 1 electron (low fluxes): 8. timing measurements Schedule forCpFMtests in BTF (April 2014)

13. “L” and “I” bars + bundle + PMTs (R7378A) “Optical AG” quartzbars • “ L” bar configuration • Lower light signal, probably due to a worstsurfacepolishing • In principle more light produced in the 3 cm fusedsilicaalong the beam direction (“L” shorterarm) Preliminary • “ I ” bar configuration • Higher light signal, probably due to a bettersurfacepolishing • In principleless light produced: lessthickness bundle

14. Optical AG FusedSilicabars Wellpolished “I” bar: itispossibletodistinguish the reflectionpointsalong the bar Worsepolished “L” bar: the light appears more widespread and the reflectionpoints are notvisible

15. Mountingconfigurations “L” and “I” bars + 3.85 mm glass “window” + PMT2 (BA1512) Withoutwindow: Withwindow: 10.5 mV @ (800 kV) 6.0 mV @ (800 kV) Reductionof the signal isabout 40 % • Flange brazedconfiguration • Better light transport (no viewport • interfaces) • Bettermechanicalstrength • Loss of light in the brazedpoints • Technologicalproblemstobraze • FusedSilicawith metal alloys • Viewport configuration • Worst light transport (viewport • interfaces) • More complex set-up • No technologicalproblems

16. I bar with + bundle + PMT1 last run 235(low flux) Online analysis Preliminary Preliminary We have a signal even in the single-particle regime

17. Conclusions • We have evidence that the full chain (radiator + glasswindow + fiber bundle + PMTs) workswell, alsofor low fluxes • We need more time to finish analysis of the data (use charge instead of amplitude) • All the measurements need to be compared with simulations as well • We chose the “I” shape for the first CpFM (with viewport) • Different solution for a better polished “L” shape bar but none is already available • We are investigating some technological solution for the brazing of fused silica bars with metal alloys (i.e. KOVAR)

18. Thankyou especiallyto the BTF and LINAC stuff…

19. SPARE

20. Channeling effect of the charged particles in the bent crystal Mechanicallybentcrystal Usingof a secondary curvature of the crystal to guide the particles

21. Multi stage collimation as in LHC • The halo particles are removed by a cascade of amorphous targets: • Primary and secondary collimators intercept the diffusive primary halo. • Particles are repeatedly deflected by Multiple Coulomb Scattering also producing hadronic showers that is the secondary halo • Particles are finally stopped in the absorber • Masks protect the sensitive devices from tertiary halo 0 beam core primary halo 6 6.2 secondary halo & showers 7 secondary halo & showers 10 secondary collimator 1m CFC secondary collimator 1m CFC primary collimator 0.6 m CFC Normalizes aperture [σ] tertiary collimator absorber 1m W tertiary halo & showers >10 Sensitive devices (ARC, IR QUADS..) masks • Collimation efficiency in LHC ≅ 99.98% @ 3.5 TeV • Probably not enough in view of a luminosity upgrade • Basic limitation of the amorphous collimation system

22. 2011 data protons 2012 data protons (270 GeV) Reduction factor (Lam / Lch) Loss rate along the SPS ring • Loss map measurement in 2011: intensity increased from 1 bunch (I = 1.15 x 1011 p) to 48 bunches, clear reduction of the losses seen in Sextant 6. • Loss map measurement in 2012: maximum possible intensity: 3.3 x 1013protons (4 x 72 bunches with 25 ns spacing), average loss reduction in the entire ring !

24. Resultsof the simulationswithoutfibers