An experiment to measure an invariant mass of <inline-formula> <tex-math notation="LaTeX">\phi </tex-math></inline-formula> mesons in nuclear medium is planned as the J-PARC E16 experiment. A trigger ...merging module (TRG-MRG) has been developed to detect leading-edges from 256 channels of discriminator-output signals and transmit those serialized hit data to trigger decision module with four optical links. The result of the test shows enough performance of the TRG-MRG as 1-ns time-to-digital converter (TDC) and data multiplexer with four 6.25 Gb/s transceivers.
The invariant mass spectra of e+e- pairs produced in 12 GeV proton-induced nuclear reactions are measured at the KEK Proton Synchrotron. On the low-mass side of the meson peak, a significant ...enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted.
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Abstract
The J-PARC E16 experiment measures mass spectra of low-mass vector mesons,
ρ
,
ω
, and
ϕ
, in nuclei via
e
+
e
-
decays. Vector mesons are produced in
p
A reactions. A spectrometer with ...a large acceptance and a high-intensity beam up to 1
× 10
10
protons per ∼2-sec duration pulse are utilized to collect a sufficient number
of vector mesons. We have developed a spectrometer, which has two types of electron
identification detectors: a hadron blind detector (HBD) and a lead-glass calorimeter.
Commissioning runs have been performed at the J-PARC high-momentum beam line. The HBD
successfully observed on average 11 ± 1 photoelectrons for an incident electron. We achieved
the pion rejection of 0.9 ± 0.2% with the electron detection efficiency of 61 ± 4% for
the HBD, which was consistent of the expected performance.
Invariant mass spectra of e(+) e(-) pairs have been measured in 12 GeV p + A reactions to detect possible in-medium modification of vector mesons. Copper and carbon targets are used to study the ...nuclear-size dependence of e(+) e(-) invariant mass distributions. A significant excess on the low-mass side of the phi meson peak is observed in the low betagamma(= beta/square root(1-beta(2))) region of phi mesons (betagamma < 1.25) with copper targets. However, in the high betagamma region (betagamma > 1.25), spectral shapes of phi mesons are well described by the Breit-Wigner shape when experimental effects are considered. Thus, in addition to our earlier publications on rho/omega modification, this study has experimentally verified vector meson mass modification at normal nuclear density.
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The J-PARC E16 experiment was proposed to investigate the restoration of chiral symmetry at the normal nuclear density. E16 will systematically measure in-medium mass of vector mesons at J-PARC ...Hadron Experimental Facility using a 30-GeV proton beam with an intensity of 2 x 1010 protons per pulse. The E16 spectrometer was designed to detect e+e- from slowly moving vector meson, particularly the φ meson. The detector system consists of GEM tracker, Gas Cerenkov detector based on GEM and electromagnetic calorimeter made of lead-glass, whose number of channels reaches about 100,000 in total. The readout electronics, trigger system and data acquisition system for the detectors have been developed, for which level-1 trigger rate of 1-2 kHz is required under several 10 MHz interaction rate. The preparation is underway for the first beam time in 2017.
A hadron blind detector for the PHENIX experiment at RHIC Fraenkel, Z.; Kozlov, A.; Naglis, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2005, Volume:
546, Issue:
3
Journal Article
Peer reviewed
Open access
A Hadron Blind Detector (HBD) is being developed for the PHENIX experiment at RHIC. It consists of a Cherenkov radiator operated with pure
CF
4
directly coupled in a windowless configuration to a ...triple-GEM detector element with a CsI photocathode and pad readout. The HBD operates in the bandwidth 6–11.5
eV (110–200
nm). We studied the detector response to minimum ionizing particles and to electrons. We present measurements of the CsI quantum efficiency, which are in very good agreement with previously published results over the bandwidth 6–8.3
eV and extend them up to 10.3
eV. Discharge probability and aging studies of the GEMs and the CsI photocathode in pure
CF
4
are presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
DAQ-Middleware is a software framework for network-distributed data acquisition (DAQ) systems. We adopted the framework for the J-PARC E16 experiment, which requires a DAQ bandwidth of more than 660 ...MB spill (two-second spill per six-second cycle). We developed a prototype for the DAQ software and confirmed that the prototype's total throughput satisfies the requirements of the experiment.
At the J-PARC E16 experiment1, we measure mass spectra of vector mesons in nuclei from the e+e- decay channel with high precision and high statistics. We have developed the trigger system consisting ...of newly developed ASD ASICs which can extract signals from the GEM foil used as a cathode plane of the induction gap in a GEM chamber and digital electronics using FPGAs which processes binary signals from the ASIC.
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