Participation of CNS, Univ. of Tokyo in RD51. Taku Gunji Hideki Hamagaki Center for Nuclear Study The University of Tokyo

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1 Participation of CNS, Univ. of Tokyo in RD51 Taku Gunji Hideki Hamagaki Center for Nuclear Study The University of Tokyo

2 CNS-Tokyo Group Members: Hideki Hamagaki (leader) Taku Gunji (deputy) Post-docs, 5 PhD students, master students Physics interests on relativistic heavy-ion collisions RHIC-PHENIX and LHC-ALICE experiment Ring Imaging Cherenkov Counter and custom readout electronics for PHENIX Transition Radiation Detector, Forward W+Si Calorimeter R&D (incl. electronics) for the upgrade Detector R&D GEM R&D and its application (GEM-TPC, Imaging)

3 Motivation for the participation Upgrade of the ALICE Time Projection Chamber in LS (018~): High rate capability of data taking 50kHz for Pb+Pb, MHz for p+p GEM based readout and continuous readout (no gating) Issues: Stable operation (discharge, gain variation) de/dx resolution for particle identification Ion back flow Collaboration with RD51 is straight-forward for the upgrade R&D

4 Our experience with GEM R&D of GEMs has begun in 00. Three directions for the R&D by CNS Basic properties of GEM starting by using» Gain, stability, P/T dependence» Ion back flow Applications GEM-TPC prototype, Imaging detector (incl. readout electronics R&D with NiAS) Making GEMs in Japan (with RIKEN, Sci-Energy) Cylindrical holes with dry (+laser) etching method Newly developed GEMs and properties» Thick-GEM (0um, 150um),» Resistive-GEM, Glass-GEM

5 5 R&D of GEM-TPC Building TPC Prototype in 003 Endcap can be replaced with GEM or MWPC End cap cm cm Preamp+ diff. driver (AD8058, AD813) cτ=1us Field cage 36x17x17cm3 115 Au strips 1MΩ bwt. strips Gas vessel 60x9x9cm3

6 R&D of GEM-TPC Beamtest in 003/00 (MWPC/GEM readout) T. Isobe et al. NIM A 56 (006), S. X. Oda et al. NIM A 566 (006), P Ar+CH6(30%) CF R : P chevron B : P rect. Y : Ar+C H 6 rect. G : CF chevron

7 GEMs made in Japan Many development of Making GEMs in Japan : Chemical etching CNS-RIEKN-SciEnergy: Dry (Plasma+Laser) etching NIM A55, 59, 00 Cylindrical shape à thicker GEM (0-150um) CERN- GEM CNS- GEM Etching method chemical plasma plasma+laser Cross- secson of GEM hole bi- conical shape cylindrical shape

8 Basic studies of GEMs Gain, Stability, P/T dependence Gain Ar(90%)/CH (%) Gain Ar(70%)/CO (30%) Gain Ar(90%)/CH (%) t [hours] Gain Ar(70%)/CO (30%) V GEM [V] V GEM [V] t [hours] Ratio Ar(90%)/CH (%) Ratio Ar(70%)/CO (30%) Measurement by Y. Yamaguchi P/T [Torr/K] P/T [Torr/K]

9 Activity Plans in RD51 and Resource Efforts to the ALICE-GEM-TPC upgrade: 1: Systematic measurements of Ion back flow (<0.5%) and search for optimal solutions Yorito Yamaguchi joined in this measurement at RD51-lab. : Simulation studies for ion back flow Taku Gunji joined in this effort with great help by Rob. (3: electronics? Production in Japan?) Man power: Prof. H. Hamagaki (mostly in Japan) T. Gunji (mostly in CERN), Y. Yamaguchi (mostly in CERN) S. Hayashi (mostly in CERN), Y. Sekiguchi (mostly in Japan) K. Terasaki (Japan/CERN)