Abstract The MEG II experiment based at PSI (Zuerich, Switzerland) has been committed and is taking data since 2021 to improve sensitivity on the decay μ + → e + γ . The pixelated Timing Counter ...(pTC), consisting of two arrays of 512 5 mm thick scintillator pixel each, read out by 6 3×3 mm 2 , 50 μm cell, Silicon Photomultipliers (SiPMs) from AdvanSiD, for a total of 6144 SiPM, achieves an overall resolution in the positron impact time of ∼43 ps when exploiting multiple measurements. To additionally improve this resolution, 4×4 mm 2 , 40 μm cell SiPMs have been selected to substitute a fraction of the old ones (about 1000 of them overall). By means of an automated test system, a first group of them has been characterized (measuring their breakdown voltage and their I-V curves), to match as much as possible SiPMs with the same gains in each pixel, in order to maximize the pixel time resolution. Such automated test system will be presented, together with some preliminary results on single pixel time resolution and the expectations of the average time resolution of the pTC in the coming years.
Large volume Liquid Argon Time Projection Chambers (LAr-TPC) are used and proposed for neutrino physics and rare event search. Most of these detectors make use of the scintillation light of liquid ...argon for trigger purposes. Two different approaches can be adopted to provide these detectors with an effective trigger system, relying upon analog or digital processing of signal coming from photodetectors, like photomultiplier tubes or silicon photomultipliers. Each method presents advantages and drawbacks, so the implementation of a hybrid solution can benefit from both approaches. To this purpose, an innovative electronic board prototype has been designed and proposed for the use in large volume LAr-TPC detectors.
Multigap RPC time resolution to 511 keV annihilation photons Belli, G.; Gabusi, M.; Musitelli, G. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2015, Letnik:
781
Journal Article
Recenzirano
Odprti dostop
The time resolution of Multigap Resistive Plate Chambers (MRPCs) to 511 keV gamma rays has been investigated using a super(22)Na source and four detectors. The MRPCs time resolution has been derived ...from the Time-of-Flight information, measured from pairs of space correlated triggered events. A GEANT4 simulation has been performed to analyze possible setup contributions and to support experimental results. A time resolution (FWHM) of 312 ps and 376 ps has been measured for a single MRPC with four 250 mu m gas gaps by considering respectively one and two independent pairs of detectors. These values, endorsed by the GEANT4 simulation, represent a good result compared to those reported in the literature.
Time-of-flight detectors, based on scintillation counters, may use conventional photomultipliers for the readout. Problems arise in presence of external magnetic fields. SiPMT arrays are insensitive ...to magnetic fields and may be a suitable option to replace photomultipliers. Timing performances for several types of SiPMT arrays have been studied and results are presented.
The final results of the search for the lepton flavour violating decay
μ
+
→
e
+
γ
based on the full dataset collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013 and ...totalling
7.5
×
10
14
stopped muons on target are presented. No significant excess of events is observed in the dataset with respect to the expected background and a new upper limit on the branching ratio of this decay of
B
(
μ
+
→
e
+
γ
)
<
4.2
×
10
-
13
(90 % confidence level) is established, which represents the most stringent limit on the existence of this decay to date.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The MEG detector for μ+→e+γ decay search Adam, J.; Bai, X.; Baldini, A. M. ...
European physical journal. C, Particles and fields,
04/2013, Letnik:
73, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The MEG (Mu to Electron Gamma) experiment has been running at the Paul Scherrer Institut (PSI), Switzerland since 2008 to search for the decay
μ
+
→e
+
γ
by using one of the most intense continuous
μ
...+
beams in the world. This paper presents the MEG components: the positron spectrometer, including a thin target, a superconducting magnet, a set of drift chambers for measuring the muon decay vertex and the positron momentum, a timing counter for measuring the positron time, and a liquid xenon detector for measuring the photon energy, position and time. The trigger system, the read-out electronics and the data acquisition system are also presented in detail. The paper is completed with a description of the equipment and techniques developed for the calibration in time and energy and the simulation of the whole apparatus.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The high precision measurement of the hyperfine splitting of the muonic-hydrogen atom ground state with pulsed and intense muon beam requires careful technological choices both in the construction of ...a gas target and of the detectors. In June 2014, the pressurized gas target of the FAMU experiment was exposed to the low energy pulsed muon beam at the RIKEN RAL muon facility. The objectives of the test were the characterization of the target, the hodoscope and the X-ray detectors. The apparatus consisted of a beam hodoscope and X-rays detectors made with high purity Germanium and Lanthanum Bromide crystals. In this paper the experimental setup is described and the results of the detector characterization are presented.
A search for the decay
μ
+
→
e
+
γ
, performed at PSI and based on data from the initial three months of operation of the MEG experiment, yields an upper limit on the branching ratio of
BR
(
μ
+
→
e
...+
γ
)
⩽
2.8
×
10
−
11
(90% C.L.). This corresponds to the measurement of positrons and photons from
∼
10
14
stopped
μ
+
-decays by means of a superconducting positron spectrometer and a 900 litre liquid xenon photon detector.
Pixelated resistive Micromegas detector for high-rate environment Alviggi, M.; Camerlingo, M.T.; Pietra, M. Della ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2022, Letnik:
1041
Journal Article
Recenzirano
The R&D work reported in this paper has been devoted to the production and test of pixelated resistive micromegas detectors able to track particles in a high-rate environment, up to 10MHz/cm2, ...keeping a stable gain and a good spatial resolution. To pursue our goal, we had to reduce the occupancy by increasing the detector granularity and this has been done by changing the read-out anodes from the usual strips to pads. This minor change in the electrodes layout drastically increased the difficulty of implementing a resistive structure to protect the anodes from sparking. We present the results of the tests performed on four prototypes, with different protection schemes, showing it is possible to reach the desired rate with high gain, high efficiency and good position resolution. The response to X-rays from low (55Fe source) to high (X-rays generator) rates, as well as to beams of ionizing particles is reported.
The MEGII Timing Counter will measure the positron time of arrival with a resolution of ~ 30ps relying on two arrays of scintillator pixels read out by 6144 Silicon Photomultipliers (SiPMs) from ...AdvanSiD. They are characterised, measuring their breakdown voltage, to assure that the gains of the SiPMs of each pixel are as uniform as possible, to maximise the pixel resolution. Gain measurements have also been performed.
•Characterisation of SiPMs for MEG-II Timing Counter is illustrated.•SiPMs breakdown voltage and gain measurement are reported.•The criterion for the choice of each single pixel SiPMs is explained.
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