Speaker
Hiroyuki Sako
(Japan Atomic Research Agency)
Description
We have been developing a TPC using GEMs and a gating grid to search for the H-dibaryon at J-PARC with high rate hadron beams up to 10^6 count per second (cps) /cm^2.
The TPC consists of an octagonal-shape drift cage of 50 cm diameter and 55 cm height, filled with Ar-CH_4 (90:10) gas, and the end cap chamber consisting of a gating grid plane, 3-layer GEMs, and a pad plane. The TPC is operated in dipole magnetic field of 1 T in parallel to the drift electric field. The horizontal position resolution is expected to be better than 300 um.
We have built a small prototype TPC and performed a beam test. The position shift due to positive-ion feedback was suppressed within +-0.2 mm both in transverse and longitudinal directions at the beam rate up to 5x10^5 cps/cm2. Detection efficiency was 97 % per pad row at low beam rate (10^3 cps/cm2), and 90 % at high beam rate (10^6 cps/cm2).
We also performed a laser test of the prototype in magnetic field, and observed expected improvement of the position resolution due to the magnetic field.
We show also the status of the full-size TPC development.
Primary author
Hiroyuki Sako
(Japan Atomic Research Agency)
Co-authors
Prof.
KenIchi Imai
(Japan Atomic Energy Agency)
Dr
Shoichi Hasegawa
(Japan Atomic Energy Agency)
susumu sato
(jaea)
