A time projection chamber with GEM-based readout

Abstract

For the International Large Detector concept at the planned International Linear Collider, the use of time projection chambers (TPC) with micro-pattern gas detector readout as the main tracking detector is investigated. In this paper, results from a prototype TPC, placed in a 1 T solenoidal field and read out with three independent GEM-based readout modules, are reported. The TPC was exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for reconstructing hits, the measurement of the drift velocity, the space point resolution and the control of field inhomogeneities are presented.

Measurement of the electron transmission rate of the gating foil for the TPC of the ILC experiment

“…The dE/dx resolutions in the absence and presence of the gating foil will be studied in a beam test using the large prototype [16] in order to confirm the expectation above.…”

“…A simulation shows that the displacement is small enough even at B = 3.5 T for small ∆V [21]. We need demonstration, however, in a strong axial magnetic field of 3 -4 T. As a first step, this is to be confirmed in a beam test at B = 1 T by measuring the spatial resolution of a large prototype TPC [16], with and without the gating foil. Deflected electrons cause the degradation of the azimuthal spatial resolution, in addition to that due to the loss of primary electrons at the gating foil.…”

Gaseous and dual-phase time projection chambers for imaging rare processes

“…At last, this brief TPC overview would not be complete without mentioning the new generation of TPCs used as trackers at various spectrometers like for instance Crystal Ball [423], FOPI [424], super-FRS [425], NICA [426] and certainly those for future colliders (e.g. ILC [427] and CPEC [428]). Although with smaller drift distances, radial/curved TPCs have been popularized recently, too (e.g., [47,48]).…”

Studies on GEM modules for a Large Prototype TPC for the ILC

“…It is evident that the goal of rφ point resolution of < 100 µm can be achieved if the gas quality and purity are tightly controlled [4].…”

“…The residuals for these distortion corrections are obtained from a sub-sample (10%) of the available data for statistical independence and applied to the remaining events taken with magnetic field 1 T. The results of the alignment correction and additionally, of the distortion corrections are shown inFigure 2. Data points showing the mean hit position in rφ with respect to the track position at 1 T after the alignment corrections (blue) and the result after the distortion effects have been corrected for (green)[4].Once the distortions have been corrected for, the single point resolution can be determined. The single point resolution in the rφ and z direction is expressed σ σ 0,rφ/z [µm] N ef f A [m −1 ] rφ 71.0 ± 1.2 39.8 ± 2.0 0.495 ± 0.097 z 306.3 ± 0.8 39.5 ± 1.6 0.529 ± 0.084 Results of the fit of equation 1 to the measured point resolution in rφ and z respectively shown in Figure 3a,b [4].…”