Detector R&D: J-PARC-E16 K. Ozawa (Univ. of Tokyo) for the E16 collaboration Condensates and Spectrum We can link condensates and vector meson spectrum. The relation is established robustly. Vacuum q Vacuum q QCD sum rule Experimental Assume results Next Experiment vector meson spectral function Calculate amout of mV quark condensate using QCD sum rule. T.Hatsuda and S. Lee, PRC 46 (1992) R34 Average of Imaginary part of P(w2) vector meson spectral function Model Prediction Calculation Average of measured spectra Mass mV* Shift: B 1 ; ) for 0.03 mmf = m 0 (1 - / 0 0 =V 0.03 Spectrum 2008/12/06 Need large statics Nagoya, K. Ozawa p 2 New Spectrometer E16 Spectrometer KEK 5 times larger acceptance for pairs Cope with 10 times larger beam intensity!! 2 times larger cross section 2008/12/06 Nagoya, K. Ozawa statistics!! Total, 100 times higher 3 Major components Prototype is made and being tested Magnet modification GEM Tracker Gas Cherenkov for e-ID Gas Cherenkov for e-ID EM Calorimeter 2008/12/06 Nagoya, K. Ozawa 4 GEM TRACKER 2008/12/06 Nagoya, K. Ozawa 5 Required Resolution • Momentum and mass resolution are evaluated based on KEK knowledge. KEK 300 mm 200 mm 100 mm 50 mm – Position resolution: • 300 mm for E325 • 50 mm, 100 mm, 200 mm, and 300 mm for J-PARC Momentum Resolution – Multiple scattering [GeV/c] • Radiation length of detectors are increased for GEM foils – Larger acceptance for J-PARC J-PARC To have the improved mass resolution, Target Resolution is 100 mm It can be achieved 0.7 mm pitch and strip charge information. 2008/12/06 KEK Nagoya, K. Ozawa 6 [mm] mass res. v.s. position res. GEM Tracker Collaboration with KEK • To cover large acceptance and cope with high counting rate, 3 layers of GEM trackers are used. • Similar to COMPASS detector – Use 3 layers in magnetic field Kapton – Extend to large acceptance • Challenge (d=50μm) : – Long term stability – Mechanical support with low radiation length – Readout Rate issue: Cupper 2 5 kHz/mm is expected at J-PARC (d=5μm) with 700 mm pitch x 100mm height COMPASS detector is working Up to 25 kHz/mm2 (400 mm pitch) GEM detector will work 2008/12/06 Nagoya, K. Ozawa COMPASS detector (NIM A535, 314) 7 GEM and Read out • GEM foils made in Japan (SciEnergy) Collaboration with KEK Relative Gain with 3 GEM foils Japanese • 2-D strip readout configuration Ar-CO2 CERN NIM A425(1999)254 2008/12/06 Nagoya, K. Ozawa 8 R&D @ Tokyo Purpose: Develop a GEM tracker Evaluate specifications Position resolution Efficiency Rate dependence Current Configuration: 3 GEM foils p-10 gas 2-D strip Both side 0.8 mm pitch Copy of KEK’s 2008/12/06 Nagoya, K. Ozawa 9 Signals TOP We can see signals from both sides. Signal from bottom surface is distorted. Already known problem by KEK group. Bottom TOP1 Bottom1 Bottom2 TOP2 Strips on top surface 2008/12/06 Strips on bottom surface Nagoya, K. Ozawa 10 Check with X-ray Strip1 Strip2 Sum Position Fe-55 X-ray Source Strip3 Position Sum of 3 strips distribution is looks reasonable almost reasonable. distribution. Beam test is done. 2008/12/06 Nagoya, K. Ozawa Results of resolution will be appeared soon. 11 GAS CHERENKOV 2008/12/06 Nagoya, K. Ozawa 12 Gas Cherenkov Detector • Electron Identification using gas cherenkov • Used for low momentum electron – Mirror and PMT, traditionally • Difficulty for Large acceptance Requirement of large acceptance at J-PARC E16 experiment Photo Cathode + GEM for amplification No Mirror Used @ KEK-PS E325 • CSI photo-cathod – UV sensitive (6 eV, 200nm) – High quantum efficiency 2008/12/06 Nagoya, K. Ozawa 13 Measurements of Q.E. Existing data by Weizmann Inst. • We got a consistent result with existing data. • Based on this measurements, the number of photoelectron with 84 cm long radiator is estimated as 65. 2008/12/06 Nagoya, K. Ozawa 14 Old beam test @ Hiroshima • Operation 1*1cm Readout Pad 5x5 used – Pure CF4 (cosθc=0.035) – CsI GEM • 150V – Other GEM • 490V (~104) Light Shield – Water ~ 1ppm • Inverse field • Light shade ON – dE/dx (1mm) • Light shade OFF – dE/dx (1mm) + Light 2008/12/06 Electrons from ionization Nagoya, K. Ozawa 15 Results Arbitrary Unit Inverse field, light shield on, dE/dx (1mm) Only Inverse field, light shield off, dE/dx (1mm) + Light Clear signal for energy loss 7 fc 10 fc Small difference, statistically It can be Cherenkov origin. New R&D is underway at RIKEN. Results will be appeared soon. 2008/12/06 0 Ozawa 20Nagoya, K.40 60 80 16 [Charge] Summary • For J-PARC E16, a GEM based spectrometer is proposed to cope with high interaction rate and have large acceptance. • R&D has started for J-PARC at Tokyo and RIKEN. GEM tracker with 2-D strip read out is being developed. First brief result of R&D is appeared. • Cherenkov counter using CSI photocathode and GEM readout is the essential part to extend the acceptance. R&D is on-going. 2008/12/06 Nagoya, K. Ozawa 17 Back up Issue: counting Rate • Interaction rate is 106 Hz at KEK (x10 @J-PARC) • However, beam halo can not be ignored • For example, actual condition at KEK is following. – 350 kHz at the most forward cell of Drift Chamber • At radius of 200 mm and the horizontal angle of 6° • 3.5mm width and 220 mm height – Mostly from beam halo • Extrapolate to J-PARC – – – – 10 times higher beam intensity shorter beam-extraction duration 3.5 MHz is expected. 10 times finer segments are required • 0.7 mm pitch x 100mm height That’s the main issue for spectrometer design. We have to develop the detector which cope with 10 times larger rate. 2008/12/06 Nagoya, K. Ozawa 19 Detectors in high counting • MWPC limitation – Wire spacing: 1~2 mm – Gain dropping @ high rate • Micro strip gas chamber – Discharge problem • Micromegas MWPC – Another candidate • GEM – Flat gain up to 105 Hz/mm2 – I like flexibility of configuration – Good characteristics of signal • Signal is generated by electron • Not by ion • No ion tail and pole cancellation electronics 2008/12/06 I took these 104 105 GEM Nagoya, K. Ozawa ideas and figures from F. Sauli’s presentation at XIV 20 GIORNATE DI STUDIO SUI RIVELATORI Villa Gualino 10-13 Febbraio 2004 What can be achieved? Pb f f Modified f f f f ff f f f from Proton [GeV/c2] High resolution Invariant mass in medium Nagoya, K. Ozawa calculate quark condensate 2008/12/06 21 Pictures from PHENIX signal electron partner positron needed for rejection In PHENIX IR Globe box Evaporate machine 2008/12/06 Nagoya, K. Ozawa 22 CSI photo cathode • Transmissive type is used – Suitable with GEM – Relatively high quantum efficiency – Low photon feedback Transmissive By Weitzman Vapor deposition on GEM By Hamamatsu ５ １０ CSI Q. E. 2008/12/06 １５ [eV] Nagoya, K. Ozawa CsI Au Ni Cu Kapton Cu 23 In reality 2008/12/06 Nagoya, K. Ozawa 24
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