Space Charge (SC) distortions are some of the main issues for high-resolution Time Projection Chambers (TPC). The two main SC sources are those from primary ionizations and those that result from ...amplification stages. The gain stages are required to increase the electron (e-) signal above electronics noise levels, but this inevitably creates extra ions. These ions can enter the drift region and distort the electric field, and thus lower the detector performance. We will present a brief motivation for our Ion Back Flow (IBF) studies along with explanations of existing techniques and our simulation results to reduce IBF. We propose several mesh structures along with static bi-polar gating. Further, we discuss position distortions in e- trajectories due to a static bi-polar grid and use these distortions to compensate for non-linear responses of our Zig-Zag pad readout.
Due to their simplicity and versatility of design, straight strip or rectangular pad anode structures are frequently used with micropattern gas detectors (MPGDs) to reconstruct high-precision space ...points for various tracking applications. The particle impact point is typically determined by interpolating the charge collected by several neighboring strips. However, to effectively extract the inherent positional information, the lateral spacing of the straight strips must be comparable to or preferably smaller than the full extent of the incident charge cloud. In contrast, highly interleaved anode patterns, such as zigzags, can adequately sample the incident charge with a pitch appreciably larger than the charge cloud. This has the considerable advantage of providing the same performance while requiring far fewer instrumented channels. Additionally, the geometric parameters defining such zigzag structures may be tuned to provide a near-uniform detector response along and perpendicular to the sensitive coordinate, without the need for so-called "pad response functions," while simultaneously maintaining excellent position resolution. We have measured the position resolution of a variety of zigzag-shaped anode patterns optimized for various MPGDs, including gas electron multiplyer (GEM), Micromegas, and micro-resistive-well (<inline-formula> <tex-math notation="LaTeX">\mu </tex-math></inline-formula>RWELL) and compared this performance with the same detectors equipped with straight strips of varying pitch. We report on the performance results of each readout structure, evaluated under identical conditions in a test beam.
We have developed highly interleaved zigzag-shaped electrodes for collecting charge on the readout plane of various micropattern gaseous detectors (MPGDs), including gas electron multiplier (GEM) and ...micromega detectors. An optimized zigzag pad (or strip) anode can greatly enhance charge sharing among neighboring pads compared to traditional straight strip or rectangular pad designs and as a result can deliver excellent position resolution with minimal channel count, while exhibiting a virtually uniform response across the detector. We have systematically studied the effects of varying the parameters that define the zigzag geometry using simulations and have measured several printed circuit boards (PCBs) comprising a range of zigzag designs. Recently, we have employed laser ablation to generate zigzag patterns with pad-to-pad gaps smaller than 1 mil (or 25 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>). Reducing the gap well below the 3-mil limit imposed by traditional chemical etching has allowed the production of zigzag electrodes with unprecedentedly small feature sizes. In turn, laser-etched zigzag PCBs were shown to exhibit markedly improved performance over earlier generation PCBs, with position resolutions below 50 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> for a 2-mm pitch. This article will explore in detail the dependence of the position resolution on the structural parameters of a zigzag-shaped anode, specifically for the case of a quadruple GEM detector.
A combined time projection chamber-Cherenkov (TPCC) prototype detector has been developed as part of the detector research and development program for a future electron-ion collider (EIC). The ...prototype was tested at the Fermilab test beam facility (FTBF) to provide a proof of the principle to demonstrate the ability to measure particle tracks and provide particle identification (PID) information within a common detector volume. The time projection chamber (TPC) portion consists of a <inline-formula> <tex-math notation="LaTeX">10 \times 10 \times 10 </tex-math></inline-formula> cm 3 field cage, which delivers charge from tracks to a quadruple gas electron multiplier (GEM) with zigzag-shaped charge collection anodes. The Cherenkov portion consists of a photosensitive quadruple GEM detector with a CsI photocathode. As tracks pass through the drift volume of the TPC, the generated Cherenkov light is able to escape through sparsely arranged wires making up one side of the field cage, facing the CsI photocathode. The Cherenkov detector is thus operated in a windowless, proximity focused configuration for high efficiency. Pure CF 4 is used as the working gas for both detector components, mainly due to its transparency into the deep UV, as well as its high N 0 . Results from the beam test, including the position resolution as well as the particle id capabilities of the detector, are discussed in this paper.
Abstract
The search for a dark photon holds considerable interest in the physics community. Such a force carrier would begin to illuminate the dark sector. Many experiments have searched for such a ...particle, but so far it has proven elusive. In recent years the concept of a low mass dark photon has gained popularity in the physics community. Of particular recent interest is the
8
Be and
4
He anomaly, which could be explained by a new fifth force carrier with a mass of 17 MeV/
c
2
. The proposed Darklight experiment would search for this potential low mass force carrier at ARIEL in the 10-20 MeV/
c
2
e
+
e
−
invariant mass range. This proceeding will focus on the experimental design and physics case of the Darklight experiment.
The Small Area Tracking system of the COMPASS experiment at CERN includes a set of 20 large area, fast position-sensitive Gas Electron Multiplier detectors, designed to reliably operate in the harsh ...radiation environment of the experiment. We describe in detail the design, choice of materials, assembly procedures and quality controls used to manufacture the devices. The test procedure in the laboratory, the performance in test beams and in the initial commissioning phase in the experiment are presented and discussed.
Aging measurements with the Gas Electron Multiplier (GEM) Altunbas, M.C.; Dehmelt, K.; Kappler, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2003, Volume:
515, Issue:
1
Journal Article
Peer reviewed
Open access
Continuing previous aging measurements with detectors based on the Gas Electron Multiplier (GEM), we investigated a
31×31
cm
2
triple-GEM detector, as used in the small area tracking of the COMPASS ...experiment at CERN. With a detector identical to those installed in the experiment, long-term high-rate exposures to
8.9
keV
X-ray radiation were performed to study its aging properties. In standard operation conditions, with Ar/CO
2 (70:30) gas filling and operated at an effective gain of 8.5×10
3, no change in gain and energy resolution is observed after collecting a total charge of
7
mC/
mm
2
, corresponding to seven years of normal operation.
This observation confirms previous results demonstrating the relative insensitivity of GEM detectors to aging, even when manufactured with common materials.
PHENIX reports differential cross sections of μμ pairs from semileptonic heavy-flavor decays and the Drell-Yan production mechanism measured in p+p collisions at s=200 GeV at forward and backward ...rapidity (1.2<|η|<2.2). The μμ pairs from cc¯, bb¯, and Drell-Yan are separated using a template fit to unlike- and like-sign muon pair spectra in mass and pT. The azimuthal opening angle correlation between the muons from cc¯ and bb¯ decays and the pair-pT distributions are compared to distributions generated using PYTHIA and POWHEG models, which both include next-to-leading order processes. The measured distributions for pairs from cc¯ are consistent with PYTHIA calculations. The cc¯ data present narrower azimuthal correlations and softer pT distributions compared to distributions generated from POWHEG. The bb¯ data are well described by both models. The extrapolated total cross section for bottom production is 3.75±0.24(stat)±0.500.35(syst)±0.45(global) μb, which is consistent with previous measurements at the Relativistic Heavy Ion Collider in the same system at the same collision energy and is approximately a factor of 2 higher than the central value calculated with theoretical models. The measured Drell-Yan cross section is in good agreement with next-to-leading-order quantum-chromodynamics calculations.
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