We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop ...a new optical system to accumulate about 10 kW power using a gyrotron, a mode converter, and a Fabry-Pérot cavity. The hyperfine transition has been observed with a significance of 5.4 standard deviations. The transition probability is measured to be A = 3.1(-1.2)(+1.6) × 10(-8) s(-1) for the first time, which is in good agreement with the theoretical value of 3.37 × 10(-8) s(-1).
The technological prototype of the CALICE highly granular silicon–tungsten electromagnetic calorimeter (SiW-ECAL) was tested in a beam at DESY in 2017. The setup comprised seven layers of silicon ...sensors. Each layer comprised four sensors, with each sensor containing an array of 256 5.5×5.5 mm2 silicon PIN diodes. The four sensors covered a total area of 18 × 18 cm and comprised a total of 1024 channels. The readout was split into a trigger line and a charge signal line. Key performance results for signal over noise for the two output lines are presented, together with a study of the uniformity of the detector response. Measurements of the response to electrons for the tungsten loaded version of the detector are also presented.
For the past few years we have been developing position sensitive silicon detectors (PSDs) which have an electrode at each of four corners so that incident position of a charged particle can be ...obtained with signal from the electrodes. It is expected that the position resolution of the silicon-tungsten electromagnetic calorimeter (SiW-ECAL) of the International Large Detector (ILD) will be improved by introducing PSDs to detection layers. In the previous production we found that the charge separation is not optimal due to the readout impedance. To solve the issue, we produced new PSDs with higher surface resistance with an additional resistive layer on the surface. We also implemented several techniques to decrease position distortion and increase signal-to-noise ratio which are essential for optimal position resolution. We present first measurements of the performance of one new PSD using a strontium 90 source, and using the Skiroc2-CMS ASIC.
Silicon sensors with high timing resolution can help particle identification in the International Linear Collider (ILC). We are studying Low Gain Avalanche Detectors (LGADs) as a sensor with high ...timing resolution. As a step to develop LGADs we are now characterizing Avalanche Photo Diodes (APDs), which have similar multiplication structure as LGADs. Particles from radioisotopes are used for studies in this paper.
The ILD Si-W ECAL is a sampling calorimeter with tungsten absorber and highly segmented silicon layers for the International Large Detector (ILD), one of the two detector concepts for the ...International Linear Collider. SKIROC2 is an ASIC for the ILD Si-W ECAL. To investigate the issues found in prototype detectors, we prepared dedicated ASIC evaluation boards with either BGA sockets or directly soldered SKIROC2. We report a performance study with the evaluation boards, including signal-to-noise ratio and TDC performance with comparing SKIROC2 and an updated version, SKIROC2A.
A high-intensity pulsed muon beam is becoming available at the at the Japan Proton Accelerator Research Complex (J-PARC). Many experiments to study fundamental physics using this high-intensity muon ...beam are proposed. An experiment to measure the muon magnetic moment anomaly (g−2) and the muon electric dipole moment (EDM) is one of these experiments and it requires a tracking detector for positrons from muon decay. Fine segmentation is required in a detector to tolerate the high rate of positrons. The time resolution is required to be much better than the muon anomalous spin precession period while a buffer depth of a front-end electronics needs to be much longer than the accelerated muon lifetime. Requirements of this detector also meet requirements of a measurement of the muonium hyperfine structure interval at the J-PARC and another experiment to measure the proton charge radius at Tohoku University. We have developed a single-sided silicon strip sensor with a 190 μm pitch, a front-end electronics with a sampling rate of 200 MHz and a buffer memory depth of 8192, and a data acquisition system based on DAQ-Middleware for the J-PARC muon g−2/EDM experiment. We have fabricated detector modules consisting of this sensor and the front-end electronics. Performance of fabricated detector modules was evaluated at a laboratory and a beam test using the positron beam at Tohoku University. The detector is confirmed to satisfy all requirements of the experiments except for the time walk, which will be solved by the next version of a front-end electronics.
Abstract
The CALICE Semi-Digital Hadron Calorimeter technological
prototype completed in 2011 is a sampling calorimeter using Glass
Resistive Plate Chamber (GRPC) detectors as the active medium. This
...technology is one of the two options proposed for the hadron
calorimeter of the International Large Detector for the
International Linear Collider. The prototype was exposed in 2015 to
beams of muons, electrons, and pions of different energies at the
CERN Super Proton Synchrotron. The use of this technology for
future experiments requires a reliable simulation of its response
that can predict its performance. GEANT4 combined with a
digitization algorithm was used to simulate the prototype. It
describes the full path of the signal: showering, gas avalanches,
charge induction, and hit triggering. The simulation was tuned using
muon tracks and electromagnetic showers for accounting for detector
inhomogeneity and tested on hadronic showers collected in the test
beam. This publication describes developments of the digitization
algorithm. It is used to predict the stability of the detector
performance against various changes in the data-taking conditions,
including temperature, pressure, magnetic field, GRPC width
variations, and gas mixture variations. These predictions are
confronted with test beam data and provide an attempt to explain the
detector properties. The data-taking conditions such as temperature
and potential detector inhomogeneities affect energy density
measurements but have small impact on detector efficiency.
SiW ECAL for future e + e − collider Balagura, V.; Bilokin, S.; Bonis, J. ...
Journal of instrumentation,
07/2017, Letnik:
12, Številka:
7
Journal Article
Recenzirano
Calorimeters with silicon detectors have many unique features and are proposed for several world-leading experiments. We discuss the tests of the first three 18×18 cm2 layers segmented into 1024 ...pixels of the technological prototype of the silicon-tungsten electromagnetic calorimeter for a future e+e− collider. The tests have beem performed in November 2015 at CERN SPS beam line.
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