We have developed 1-inch square-shaped Micro-Channel-Plate PMT (MCP-PMT) for the barrel particle identification detector, named Time-Of-Propagation (TOP) detector, at the Belle II experiment. The TOP ...detector utilizes the precise timing measurement to reconstruct the charged particle velocity through the Cherenkov ring image and the time-of-flight information. The MCP-PMT realizes the timing measurement with <40 ps precision for single photon detection.
We have tested over 600 MCP-PMTs including spares, and installed 512 of those into the Belle II TOP detector. Along with the mass production, we have studied to improve the MCP-PMT photocathode lifetime. By applying Atomic-Layer-Deposition (ALD) technique on MCP and further residual gas reduction process, the lifetime have improved significantly. The improved PMTs are also installed. To understand the mechanism of photocathode deterioration, we have measured feed-backed ion’s signals using developed MCP-PMTs and studied the correlation between the rate and the lifetime.
•Develop new particle identification device for Belle II, named TOP detector.•Produced and tested >600 Micro-Channel-Plate PMTs for TOP detector.•Studied to improve the MCP-PMT photocathode lifetime.•Confirmed long lifetime by applying ALD coating on MCP and further gas reduction.•Found no clear correlation between the rate of feed-backed ions and the lifetime.
Development of a TOP counter for the Super B factory Inami, K.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2008, Letnik:
595, Številka:
1
Journal Article
Recenzirano
We will in this paper discuss a novel concept for a ring imaging Cherenkov detector. It measures the time of propagation of the Cherenkov photons in a quartz radiator. The photon detectors are ...micro-channel-plate photo-multipliers with GaAsP photo-cathodes. The performance has been estimated to give a separation better than
3.5
σ
between K and
π
at
4
GeV
/
c
. This detector, together with a compact focusing system to correct the chromatic effect, will have an even better resolution. We will show that it can achieve more than
4.2
σ
separation between K and
π
at
4
GeV
/
c
. This detector is well suited for experiments at the Super B factory.
TOP counter prototype R&D Inami, K.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Letnik:
639, Številka:
1
Journal Article
Recenzirano
We have been developing a Cherenkov ring-imaging counter, named TOP counter, as a particle-identification device of the Belle-II detector for the super B-factory at KEK. In this presentation, we show ...the R&D status of the TOP counter prototype. We performed a beam test using 2
m long quartz radiator and MCP-PMTs, and evaluated the number of detected photons, time resolution and chromatic effects. We developed a square-shape MCP-PMT with Hamamatsu photonics, so as to obtain a sufficient lifetime under the Belle-II environment. We improved the lifetime of the quantum efficiency by changing the internal structure and production process, and then obtained a lifetime of
>
350
mC
/
cm
2
.
Abstract
This paper introduces a new approach to measure the muon magnetic moment anomaly $a_{\mu} = (g-2)/2$ and the muon electric dipole moment (EDM) $d_{\mu}$ at the J-PARC muon facility. The goal ...of our experiment is to measure $a_{\mu}$ and $d_{\mu}$ using an independent method with a factor of 10 lower muon momentum, and a factor of 20 smaller diameter storage-ring solenoid compared with previous and ongoing muon $g-2$ experiments with unprecedented quality of the storage magnetic field. Additional significant differences from the present experimental method include a factor of 1000 smaller transverse emittance of the muon beam (reaccelerated thermal muon beam), its efficient vertical injection into the solenoid, and tracking each decay positron from muon decay to obtain its momentum vector. The precision goal for $a_{\mu}$ is a statistical uncertainty of 450 parts per billion (ppb), similar to the present experimental uncertainty, and a systematic uncertainty less than 70 ppb. The goal for EDM is a sensitivity of $1.5\times 10^{-21}~e\cdot\mbox{cm}$.
Abstract
The disk-loaded structures (DLS) in the muon LINAC are under development for the J-PARC muon g–2/EDM experiment. Four DLSs with an accelerating gradient of 20 MV/m take charge of muon ...acceleration from 40 MeV to 212 MeV, which corresponds to 70% to 94% of the speed of light. The quasi-constant gradient type TM01-2π/3 mode DLSs with gradually varying disk spacing was designed and it was confirmed that the cumulative phase slip due to the mismatch between muon and phase velocity can be suppressed to less than 2 degrees at the frequency of 2592 MHz. In addition, the optimum synchronous phase and the lattice were investigated to satisfy the requirements of the total emittance less than 1.5π mm mrad and the momentum spread less than 0.1% in RMS.
The front-end electronics system for the Belle II Time-Of-Propagation (TOP) counter was fully installed in May 2016. The detector is a novel particle identification device for the barrel region, ...where Cherenkov ring images are reconstructed with precise timing information of each photon. The readout electronics need to have excellent timing performance for single photon detection. To exploit the benefit of high luminosity, the electronics must also be able to cope with a high input trigger rate (30 kHz) and have buffer memory which is deep enough to wait for a trigger decision (>5 μs). The TOP electronics has switching capacitor arrays to sample waveforms with 2.7 GSample/s, which allows a timing resolution of 50 ps for a single photon signal. The programmable logic and the processing system are the effective implementation to meet these requirements, where flexible optimization and step-by-step development of readout logic are possible. The system has been successfully operated in the first accelerator commissioning runs with beam collisions in 2018, where the typical trigger rate was 500Hz. Operation with a 20 kHz trigger rate was also tested.
•Readout electronics for the Belle II Time-Of-Propagation counter was installed.•A single photon is detected with timing resolution better than 100 ps.•The whole system was successfully operated in the physics run.
Multidrug resistance-associated protein 3 (MRP3) is a basolaterally localized transporter in the liver and contributes to the transport of various metabolites such as conjugates of endogenous ...compounds and drugs from hepatocytes. MRP3 expression in the human liver is low under normal physiologic conditions but is induced by drug treatment. Although several studies have identified a region necessary for the basal transcription of MRP3, no region that responds to drugs has been reported. To identify the xenobiotic-responsive elements of MRP3, we constructed a luciferase reporter plasmid containing the MRP3 5'-flanking region up to -10 kb upstream from the transcription start site. Among typical nuclear receptor ligands, clotrimazole dramatically enhanced MRP3 reporter activity in HepG2 cells, whereas rifampicin had no effect. We then conducted MRP3 reporter assays with deletion or mutation constructs to identify a clotrimazole-responsive element. The element was located approximately -6.8 kb upstream from the MRP3 transcription start site. Overexpression of the pregnane X receptor did not enhance clotrimazole-mediated transcription. We found that clotrimazole was toxic to HepG2 cells and we therefore investigated whether mitogen-activated protein kinase (MAPK) activation is involved in the transactivation of MRP3 by clotrimazole. p38 MAPK inhibitor SB203580 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole suppressed MRP3 mRNA expression induced by clotrimazole, whereas c-Jun N-terminal kinase inhibitor SP600125 (1,9-pyrazoloanthrone) and extracellular signal-regulated kinase inhibitor PD98059 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one did not. Phosphorylated p38 MAPK was detected in HepG2 cells treated with clotrimazole. These results suggest that activation of the p38 MAPK pathway induces the transcriptional activation of MRP3.
Lifetime-extended MCP-PMT Jinno, T.; Mori, T.; Ohshima, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2011, Letnik:
629, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In order to develop a long-lifetime MCP-PMT under high rates of circumstance, we investigated the degradation of the quantum efficiency (
QE) of PMT's with a multialkali photocathode. We found that ...not only positive ions, but also neutral residual gases would damage the photocathode resulting in an enhancement of the work function; their countermeasures were established in newly manufactured square-shaped MCP-PMT's with 4 or 4
×
4 multi-anodes. The performances of the PMT's were measured:
QE was stable up to an integrated amount of anode output charge of 2–3
C/cm
2, while keeping other basic performances steady, such as the time resolution for single photons (
σ
TTS
) of
≃
40
ps, a photoelectron collection efficiency (
CE) of 60%, a multiplication gain (
G) of a few ×10
6, and dark counts of 20–300
Hz. The causes of
QE degradation are discussed.
Negative muonium atom (μ+e-e-, Mu-) has unique features stimulating potential interesting for several scientific fields. Since its discovery in late 1980's in vacuum, it has been discussed that the ...production efficiency would be improved using a low-work function material. C12A7 was a well-known insulator as a constituent of alumina cement, but was recently confirmed to exhibit electric conductivity by electron doping. The C12A7 electride has relatively low-work function (2.9 eV). In this paper, the negative muonium production measurement with several materials including a C12A7 electride film will be presented.
PDF
