A new inorganic crystal Gd3Al2Ga3O12 is being developed. This crystal is suitable for electromagnetic calorimeters used in high energy physics experiments because the time constant of light emission ...is small (90 ns) and the light yield is as large as that of NaI(TI) crystals. In addition, the response of the crystal can be faster by adding doping materials. By using this crystal, we aim at developing an electromagnetic calorimeter that can distinguish neutrons from gammas. In this article, we describe how we distinguish neutrons from gammas and the results of a series of beam tests for a prototype module to evaluate the separation capability.
CsI calorimeter for the J-PARC KOTO experiment Sato, K.; Lee, J.W.; Banno, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2020, Letnik:
982, Številka:
C
Journal Article
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An electromagnetic calorimeter made of undoped CsI crystals is used in the J-PARC KOTO experiment to search for new physics beyond the standard model with the KL→π0νν̄ decay. The calorimeter is ...designed to operate in vacuum of 0.1 Pa and in a high-rate environment where the counting rate due to KL decays is O(100) kHz. A special method to calibrate the calorimeter during the data taking without using a tracking system for charged particles is reported. The energy, position, and timing resolutions of the calorimeter were evaluated in several beam tests, and the resolutions satisfy the required performance. The energy resolution with the total energy E is 0.66⊕1.81∕EGeV% in the inner region of the calorimeter.
Abstract Samples of the monolithic silicon pixel ASIC prototype produced in 2022 within the framework of the Horizon 2020 MONOLITH ERC Advanced project were irradiated with 70 MeV protons up to a ...fluence of 1 × 10 16 n eq /cm 2 , and then tested using a beam of 120 GeV/c pions. The ASIC contains a matrix of 100 μ m pitch hexagonal pixels, read out by low noise and very fast frontend electronics produced in a 130 nm SiGe BiCMOS technology process. The dependence on the proton fluence of the efficiency and the time resolution of this prototype was measured with the frontend electronics operated at a power density between 0.13 and 0.9 W/cm 2 . The testbeam data show that the detection efficiency of 99.96% measured at sensor bias voltage of 200 V before irradiation becomes 96.2% after a fluence of 1 × 10 16 n eq /cm 2 . An increase of the sensor bias voltage to 300 V provides an efficiency to 99.7% at that proton fluence. The timing resolution of 20 ps measured before irradiation rises for a proton fluence of 1 × 10 16 n eq /cm 2 to 53 and 45 ps at HV = 200 and 300 V, respectively.
Abstract
A monolithic silicon pixel prototype produced for the
MONOLITH ERC Advanced project was irradiated with 70 MeV protons up
to a fluence of 1 × 10
16
1 MeV
n
eq
/cm
2
. The ASIC contains a ...matrix of
hexagonal pixels with 100 μm pitch, readout by low-noise and
very fast SiGe HBT frontend electronics. Wafers with 50 μm
thick epilayer with a resistivity of 350 Ωcm were used to
produce a fully depleted sensor. Laboratory tests conducted with a
90
Sr source show that the detector works satisfactorily after
irradiation. The signal-to-noise ratio is not seen to change up to
fluence of 6 × 10
14
n
eq
/cm
2
. The signal
time jitter was estimated as the ratio between the voltage noise and
the signal slope at threshold. At -35°C, sensor bias voltage
of 200 V and frontend power consumption of 0.9 W/cm
2
, the time
jitter of the most-probable signal amplitude was estimated to be
σ
t
90
Sr = 21 ps for proton fluence up to
6 × 10
14
n
eq
/cm
2
and 57 ps at
1 × 10
16
n
eq
/cm
2
. Increasing the sensor
bias to 250 V and the analog voltage of the preamplifier from 1.8
to 2.0 V provides a time jitter of 40 ps at
1 × 10
16
n
eq
/cm
2
.
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.
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.
The performance of the CsI electromagnetic calorimeter to be used for the J-PARC E14 KOTO experiment for a rare decay KL→π0νν¯ was studied by using a positron beam from an accelerator. The energy, ...timing, and position resolutions for energies up to 800MeV were measured. We also developed a new method to reconstruct the incident angle of photons based on the shower shape recorded with the calorimeter, and evaluated the method to suppress possible backgrounds for KL→π0νν¯ decay signals.
We have been developing a monolithic pixel sensor for the International Linear Collider (ILC) vertex detector with the 0.2 μm FD-SOI CMOS process by LAPIS Semiconductor Co., Ltd. We aim to achieve a ...3 μm single-point resolution required for the ILC with a 20×20 μm2 pixel. Beam bunch crossing at the ILC occurs every 554 ns in 1-msec-long bunch trains with an interval of 200 ms. Each pixel must record the charge and time stamp of a hit to identify a collision bunch for event reconstruction. Necessary functions include the amplifier, comparator, shift register, analog memory and time stamp implementation in each pixel, and column ADC and Zero-suppression logic on the chip. We tested the first prototype sensor, SOFIST ver.1, with a 120 GeV proton beam at the Fermilab Test Beam Facility in January 2017. SOFIST ver.1 has a charge sensitive amplifier and two analog memories in each pixel, and an 8-bit Wilkinson-type ADC is implemented for each column on the chip. We measured the residual of the hit position to the reconstructed track. The standard deviation of the residual distribution fitted by a Gaussian is better than 3 μm.
Although the causal agent of yellows of Brassica rapa (turnip, pak choi, and narinosa) in Japan was reported in 1996 to be Fusarium oxysporum f. sp. conglutinans, this classification has remained ...inconclusive because of a lack of detailed genetic and pathogenic studies. Therefore, we analyzed the taxonomic position of this organism using Japanese isolates of F. oxysporum complex obtained from diseased individuals of various B. rapa subspecies. Phylogenetic analyses using partial sequences of the rDNA intergenic spacer region and the mating-type gene (MAT1-1-1α-box) showed that B. rapa and cabbage isolates belong to different monophyletic clades that separated at early evolutionary stages. Additionally, correlations were observed between the molecular phylogeny and the vegetative compatibility groups. Isolates from turnip, komatsuna, and narinosa (B. rapa group) did not show pathogenicity against cabbage or broccoli (B. oleracea group), although they caused severe symptoms on their original host species. In contrast, cabbage isolates had significantly higher (P = 0.05) virulence on B. oleracea than on B. rapa crops. Our results indicate that F. oxysporum complex isolates from B. rapa and B. oleracea are not only phylogenetically distinct but also differ in host specificity. Therefore, we propose a novel forma specialis, F. oxysporum f. sp. rapae, which causes yellows on B. rapa, including turnip, komatsuna, pak choi, and narinosa.
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