The measurement of the direction of WIMP-induced nuclear recoils is a compelling but technologically challenging strategy to provide an unambiguous signature of the detection of Galactic dark matter. ...Most directional detectors aim to reconstruct the dark-matter-induced nuclear recoil tracks, either in gas or solid targets. The main challenge with directional detection is the need for high spatial resolution over large volumes, which puts strong requirements on the readout technologies. In this paper we review the various detector readout technologies used by directional detectors. In particular, we summarize the challenges, advantages and drawbacks of each approach, and discuss future prospects for these technologies.
NEWAGE Miuchi, K.; Nakamura, K.; Takada, A. ...
EAS publications series,
2012, 2012-00-00, 20120101, Letnik:
53
Journal Article
NEWAGE is a direction-sensitive dark matter search experiment with a gaseous time-projection chamber. We improved the direction-sensitive dark matter limits by our underground measurement. In this ...paper, R&D activities sinse the first underground measurement are described.
The Electron Tracking Compton Camera (ETCC) has the wide energy range. We upgrade the recoil electron tracking algorithm to improve the detection efficiency. The performance of ETCC is checked by ...using F-18 (FDG) which is used for PET imaging. We have developed the ETCC for new medical imaging device and succeeded in imaging the some imaging reagents. Thus, this detector has the possibility of new medical imaging.
During the 2020–2021 winter season, we detected 6 gamma‐ray glows at Kanazawa University, Japan. Negative surface electric fields (E‐fields; in the sign convention of atmospheric electricity) were ...observed by a field mill during all the glow cases. In five of the six cases, the peak E‐field reached around −12 kV m−1, and the E‐field during the glow detection was the strongest in the interval including 3 hr before and after the detection time. Therefore, negative charges should have been dominant in the thunderclouds that produced the gamma‐ray glows, and electrons were probably accelerated and multiplied by the E‐fields between a predominantly negative charge layer and a localized positive charge layer below. In addition, we extracted 8 non‐detection cases in the 2020–2021 winter season, in which surface E‐fields were stronger than −12 kV m−1. In 5 of the 8 cases, radar echoes were inadequately developed, suggesting insufficient charge accumulation. On the other hand, the remaining 3 cases had well‐developed radar echoes, and there was no significant difference from the detection cases.
Plain Language Summary
Gamma‐ray glow is a minute‐lasting burst of high‐energy photons associated with thunderclouds. High‐energy photons are considered to originate from high‐energy electrons accelerated and multiplied in strong electric fields inside thunderclouds. When a gamma‐ray glow is detected on the ground, electrons are considered to be accelerated downward by upward electric fields. In the 2020–2021 winter season, we detected a total of 6 gamma‐ray glows during winter thunderstorms at Kanazawa University, Japan. An electric‐field monitor recorded negative electric fields at the surface during all the glow detections, indicating negative charges overhead. It suggests that the thunderclouds that produced the gamma‐ray glows were strongly charged negatively, and a localized positive charge layer existed in the lower part to produce an upward electric field for downward electron acceleration.
Key Points
In the 2020–2021 winter season, 6 gamma‐ray glows were detected at Kanazawa University, Japan, with electric‐field measurement
Surface electric fields were negative during the detection of all the gamma‐ray glows
High‐energy electrons seemed to be produced between a well‐developed negative charge region and a localized positive charge region below
For MeV gamma ray astronomy, we have developed an Electron Tracking Compton Camera (ETCC) as a MeV gamma ray telescope in the next generation. Our detector consists of a gaseous Time Projection ...Chamber (TPC), which uses μ-PIC as the two-dimensional readout detector, and a position sensitive scintillation camera. We launched a small size ETCC with a 10 cm × 10 cm × 15 cm TPC loaded on a balloon in 2006, and obtained the fluxes of diffuse cosmic and atmospheric gamma rays (SMILE-I). As the next step of SMILE-I, we have a plan of the next measurement of MeV gamma ray celestial sources like Crab Nebula with a middle size (30 cm) 3 ETCC (SMILE-II) for the test of its imaging property. For SMILE-II, we developed the new Data AcQuisition (DAQ) system of an ETCC to reduce the dead time and power consumption, including the new data acquisition algorithm of electron tracking. The detection efficiency obtained using the new algorithm is about 10 times larger than the one based on the SMILE-I's algorithm. In this record, we report the new SMILE-II ETCC DAQ system and its performances.
For MeV gamma-ray Astronomy, we have developed an Electron Tracking Compton Camera (ETCC) as a next-generation MeV gamma-ray telescope. An ETCC consists of a three-dimensional electron tracker using ...a gaseous time projection chamber (TPC) and position-sensitive gamma-ray absorbers using pixel scintillator arrays (PSAs). We carried out the balloon borne experiment in 2006 with a small size ETCC and observed successfully the fluxes of the diffuse cosmic and atmospheric gamma rays. As the next flight, we plan to observe bright celestial sources like Crab nebula and have constructed a large size ETCC. To achieve this, an effective area must be larger than 0.5cm 2 for obtaining a 3 sigma level signal for 3 hours observation. To obtain the required sensitivity, we have improved the electron track reconstruction method by updating the track encoding logic and developing a simple track analysis for the new logic. We performed ground-based experiments in the new method using a test model ETCC and measured the detection efficiency, which is found to be 10 times higher than that in the previous method and consistent with the simulation. In addition, the measured angular resolution is improved remarkably. From these results, we expect that a large size ETCC will have more than 3 times better sensitivity than the original design performance.
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