MPGD-based photon detectors for the upgrade of COMPASS RICH-1 and beyond (#1435)
1 INFN Sezione di Trieste, Trieste, Italy
After pioneering gaseous detectors of single photon for RICH applications using solid-state PhotoCathodes (PC) within the RD26 collaboration and by the realization of the MWPCs with CsI PC for the RICH detector of the COMPASS experiment at CERN SPS, in 2016 we have upgraded COMPASS RICH by novel gaseous photon detectors based on MPGD technology. Four new photon detectors, covering a total active area of 1.5 square meters, have been installed in order to cope with the challenging efficiency and stability requirements of the COMPASS physics program. The new detector architecture consists in a hybrid MPGD combination: two layers of THGEMs, the first of which also acts as a reflective PC thanks to CsI coating, are coupled to a bulk Micromegas on a pad-segmented anode; the signals are read-out by analog F-E based on the APV-25 chip. These MPGD-based single photon detectors are the first application in a running experiment.
Highlights of the COMPASS RICH-1 Photon Detectors upgrade are presented, including R&D, engineering, mass production, quality assessment. The performance of the MPGD-based photon detectors will be discussed in details.
Perspectives for further developments in the field of gaseous single photon detectors will be also mentioned.
Keywords: MPGD, novel photon detector
Demonstration of Soft X-ray 3D Scanning and Modelling with Glass GEM (#1317)
T. Fujiwara1, Y. Mitsuya2, H. Takahashi2
1 National Institute of Advanced Industrial Science and Technology (AIST), National Metrology Institute of Japan, Tskuba, Japan
We propose a new use of gaseous detector, soft X-ray CT scanner based on optical readout G-GEM detector. Imaging with soft X-rays, under 10 keV, provide excellent spectroscopic information and deliver high-contrast images of low Z number elements, such as soft tissues. In this study, we demonstrate the performance of high resolution and high sensitive digital imager with soft X-rays. The imager is based on high gain gaseous detector, Glass GEMs. The imager was stably operated and succeed in taking high resolution images to reconstruct 3D computed tomography (CT). Fine 3D X-ray CT image of a hornet was reconstructed in high contrast. Moreover, the 3D CT data was converted into 3D CAD data, and a copy of the scanned object was printed with commercial 3D printer. This work demonstrates a new use of gaseous detector; rapid and precise soft X-ray 3D scanning and modelling of soft tissues are performed.
Keywords: Glass GEM, X-ray imaging, Soft X-ray, CT, 3D printer
Performance of the CMS RPC upgrade using 2D fast timing readout system (#2329)
I. B. Laktineh1
1 IPNL, CNRS, Lyon, France
A new generation of RPC chambers capable of standing high particle flow (up to 2000 Hz/cm2) and instrumented with a precise timing readout electronics is proposed to equip two of the four high eta stations of the CMS muon system.
Doublet RPC detectors each made of two 1.4 mm HPL electrodes and separated by a gas gap of the same thickness are proposed. The new scheme reduces the amount of the avalanche charge produced by the passage of a charged particle through the detector. This improves the RPC rate capability by reducing the needed time to absorb this charge.
To keep the RPC efficiency as high as it is in the present CMR RPC system a sensitive, low noise, Front-End Electronics is needed to cope with the low charge signal. Also, to exploit the timing capability of the RPC the new electronics needs to provide a precise time measurement. An ASICS called PETIROC that has all these characteristics is proposed to read out the new chambers.
Thin (0.6 mm) Printed Circuit Board (PCB), 160 cm long, equipped with pickup strips of the same length will be inserted between the two RPC detectors. The strips of an average pitch of 0.75 cm will be read out from both ends and the arrival time difference will be used to find the particle impact along the strip to determine the Y position. Two configurations of such a challenging PCB were designed and successfully produced.
The absolute time measurement, of the RPC signal shape will be also used with the aim to reduce the data ambiguity due to the expected high pileup in the future HL-LHC.
The first results of a full RPC chamber equipped with the new readout system will be presented. The excellent time and position resolutions obtained with the new chamber thanks to the new readout system first on cosmic bench and then in a beam test at CERN will be shown. Further steps to validate completely the concept will be discussed.
Keywords: RPC, 2D Readout, timing
The spark measurement for the validation of low-resistive anode Micromegas in the ATLAS New Small Wheel upgrade (#1701)
1 Tokyo ICEPP, International Center for Elementary Particle Physics and Department of Physics, Tokyo, Japan
on behalf of the ATLAS Muon Collaboration
The New Small Wheel (NSW) will be installed on the ATLAS detector at CERN’s Large Hadron Collider (LHC) for stable operation in high luminosity environment. The NSW consists of two gaseous detectors, Resistive Micromegas (MM) and small-strip Thin Gap Chamber (sTGC). In MM detector, resistive anode is placed on copper read-out board to achieve its discharge resistance. In order to put the spark resistance into practice, ones must control anode resistivity which directly affecting performance of discharge suppressing. Previous study suggested the safety criteria for anode resistivity and the ATLAS’s MM mass production has been following the value, which is 20 +/- 200% [Mohm/cm/strip]. However, the detailed quantitative relation between spark resistance and anode resistivity is not fully understood. To achieve this, we measured spark rate of MM Read out board with different resistivity anodes.
Keywords: LHC, Micromegas
Development of a surface alpha ray detector based on μ-TPC with low background (#1015)
H. Ito1, T. Hashimoto1, T. Ikeda1, H. Ishiura1, K. Miuchi1, K. Nakamura1, Y. Takeuchi1
1 Kobe University, Graduate School of Science, Kobe, Japan
In a direct search for the dark matter, leading experiments makes use of massive and low background detectors. Particularly, the detector is required to design with low radio purity materials, whose impurities such as U-238 and Th-232 are in the ppb level. We have been developing a new detector of alpha-rays emitted from the material surface based on a time projection chamber technology. NEWAGE-0.3a, which was used to a direction-sensitive dark matter direct search in Kamioka mine underground, was modified and used. The detector has an advantage of a position sensitivity in comparison with a conventional alpha-ray detector, thus it is possible to obtain alpha–rays’ emission distribution in the sample surface. A NEWAGE-0.3a's drift plate (Cu) has a hole (10cmx10cm) in the center and the sample is set upon the hole using Cu mesh, so that the alpha rays from the sample can enter to the fiducial volume, (10cm x 10cm) x 30 cm. It was upgraded with a low alpha-emitting μ-PIC, whose impurities were reduced less than 10^-4/hr/cm^2. Furthermore, a new algorithm to determine the sense of the alpha-ray track, whether from the sample or from the μ-PIC, was developed and the sensitivity was improved by another factor 2. The energy and position calibrations were performed using Am-241 alpha-ray (5.4-5.5 MeV). The energy resolution and detection efficiency were estimated. As a result, the sensitivity as background level was improved by factor 10, to 10^-2 alphas/cm2/hr. Upgradable plans to achieve the goal of less than 10^-4 alphas/cm2/hr are also presented.
Keywords: alpha ray, Time Projection Chamber, Low radioactivity, μ-PIC
MPGD Optical Read Out for Directional Dark Matter Search (#2867)
G. Mazzitelli1, D. Pinci2, G. Cavoto2, E. Baracchini3, S. Tomassini1, F. Renga2, E. Di Marco2, C. Voena2, M. Maraffini4, C. Mancini2
1 INFN - Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Frascati, Italy
The Time Projection method is an ideal candidate to track low energy release particles. Large volumes can be readout by means of a moderate number of channels providing a complete 3D reconstruction of the charged tracks within the sensitive volume. It allows the measurement not only of the total released energy but also of the energy release density along the tracks that can be very useful for particle identification and to solve the head-tail ambiguity of the tracks. Moreover, gas represents a very interesting target to study Dark Matter interactions. In gas, nuclear recoils can travel enough to give rise to tracks long enough to be acquired and reconstructed.
Keywords: MPGD, GEM, Dark Matter, optical readout