Fabrication of low-cost, large-area prototype Si(Li) detectors for the GAPS experiment

Perez, K.; Aramaki, T.; Hailey, Charles J.; Carr, R.; Erjavec, T.; Fuke, H.; Garvin, Amani; Harper, Cassia; Kewley, Glenn; Madden, N.; Mechbal, Sarah; Rogers, F.; Saffold, N.; Tajiri, Gordon; Tokuda, K.; Williams, Jason; Yamada, Minoru

doi:10.1016/j.nima.2018.07.024

Cited by 31 publications

(21 citation statements)

References 39 publications

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“…The lifetime of minority carriers is an indicator of crystal defects and contaminants. The lifetime of ∼1 ms is enough to make a high-quality compensated region, as proven by our in-house development [31].…”

Section: Procurement Of P-type Si Crystalmentioning

confidence: 82%

“…Shimadzu Corporation, Japan, is an industryleading company of Si(Li) EDX detectors. The fabrication apparatuses and methods herein are developed by extending the work of our previous studies [28][29][30][31], while utilizing Shimadzu's techniques for quality control and cost reduction.…”

Section: Overview Of Fabrication Flowmentioning

confidence: 99%

“…Two key techniques in the GAPS Si(Li) development are a uniform Li drift in large-area Si(Li) and a suppression of leakage current at the relatively high temperature. Based on previous research on prototype detectors [28][29][30][31], we have established a mass-production method for the GAPS Si(Li) detectors. Figure 1 shows an example of a GAPS Si(Li) detector.…”

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confidence: 99%

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Developing a mass-production model of large-area Si(Li) detectors with high operating temperatures

Kozai

Fuke

Yamada

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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This study presents a fabrication process for lithium-drifted silicon (Si(Li)) detectors that, compared to previous methods, allows for mass production at a higher yield, while providing a large sensitive area and low leakage currents at relatively high temperatures. This design, developed for the unique requirements of the General Antiparticle Spectrometer (GAPS) experiment, has an overall diameter of 10 cm, with ∼9 cm of active area segmented into 8 readout strips, and an overall thickness of 2.5 mm, with 2.2 mm ( 90%) sensitive thickness. An energy resolution 4 keV full-width at half-maximum (FWHM) for 20−100 keV X-rays is required at the operating temperature ∼ − 40 • C, which is far above the liquid nitrogen temperatures conventionally used to achieve fine energy resolution. High-yield production is also required for GAPS, which consists of 1000 detectors. Our specially-developed Si crystal and custom methods of Li evaporation, diffusion and drifting allow for a thick, large-area and uniform sensitive layer. We find that retaining a thin undrifted layer on the p-side of the detector drastically reduces the leakage current, which is a dominant component of the energy resolution at these temperatures. A guard-ring structure and optimal etching of the detec- tor surface are also confirmed to suppress the leakage current. We report on the mass production of these detectors that is ongoing now, and demonstrate it is capable of delivering a high yield of ∼90%.We present here a high-yield mass production process for lithium-drifted silicon (Si(Li)) detectors that meet the unique requirements of the General Antiparticle Spectrometer (GAPS) experiment. GAPS is a balloon-borne experiment that aims to survey low-energy (<0.25 GeV/n) cosmic-ray antinuclei for the first time, by adopting a novel detection concept based on the physics of exotic atoms [1][2][3][4]. Low-energy cosmic-ray antinuclei, especially antideuterons, are predicted to be distinctive probes for the dark matter annihilation or decay occurring in the Galactic halo [1,[5][6][7][8][9]. Precise measurement of the low-energy antiproton spectra will also provide crucial information on the source and propagation mechanisms of cosmic rays [10][11][12][13]. GAPS sensitivities to antideuterons and antiprotons are discussed in [14] and [13], and capabilities for antihelium detection are being evaluated. The first flight of GAPS via a NASA Antarctic long duration balloon is planned for late 2021.GAPS is comprised of a 1.6 m W × 1.6 m D × 1.0 m H tracker made of Si(Li) detectors surrounded by a time-of-flight (TOF) system made of plastic scintillator paddles. A low-energy antinucleus triggered by the TOF is slowed and captured by the Si(Li) detector array, forming an excited exotic atom with a silicon nucleus. It immediately decays, radiating de-excitation X-rays of characteristic energies. The antinucleus then annihilates with the silicon nucleus, producing pions and protons with a multiplicity that scales with the incident antinucleus mass. The surrounding Si(Li)...

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Section: Procurement Of P-type Si Crystalmentioning

confidence: 82%

Section: Overview Of Fabrication Flowmentioning

confidence: 99%

mentioning

confidence: 99%

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Developing a mass-production model of large-area Si(Li) detectors with high operating temperatures

Kozai

Fuke

Yamada

et al. 2019

Nuclear Instruments and Methods in Physics Research Section A:

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“…To achieve sensitivity to the very low antideuteron flux, more than 10 m 2 of active Si area is required. Since limited power is available to the cooling system on the balloon flight, the operation temperature is -35 to -45 C, significantly higher than that of typical silicon X-ray detectors [4].…”

Section: The Si(li) Trackermentioning

confidence: 96%

Front-end Electronics for the GAPS Tracker

Scotti¹,

Boiano²,

Fabris³

et al. 2019

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019)

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The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon-borne mission to indirectly search for dark matter through sensitive observation of cosmic antiparticles. The first flight is planned for late 2021. GAPS is the first experiment optimized specifically for detection of low-energy (< 0.25 GeV/n) antideuterons, which are recognized as distinctive signals from dark matter annihilation or decay in the Galactic halo. To achieve high sensitivity to cosmic antinuclei in this low-energy range, GAPS uses a novel particle identification method based on exotic atom capture and decay. The GAPS instrument consists of ten planes of 1440 10 cm-diameter, 2.5 mm-thick, 8-strip lithium drifted silicon (Si(Li)) detectors, which constitutes the tracker, surrounded by a plastic scintillator time-of-flight system. A new fabrication technique has been developed to satisfy the stringent requirements of the mission. In this contribution, we describe the front-end electronics of the tracker of GAPS. The system is composed of front-end ASICs and power supplies. The ASICs provide readout and digitization of the signal (with an 11-bit ADC) in a wide dynamic range (10 keV-100 MeV). Every ASIC has 32 channels and performs the readout for 4 detectors, for a total amount of 11520 channels. The ASIC analog front-end is based on a dynamic compression technique to handle a large range of signal amplitudes and features a low noise performance, achieving the required 4 keV resolution at low energies. The power system supplies both bias voltages for the Si(Li) detectors and low voltages for the electronics.

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“…The main target of GAPS consists of multiple layers of Si(Li) wafers used for vertex finding, particle tracking, and high energy X-ray detection. For a detailed description of the fabrication and characterization of these detectors see [5]. A custom ASIC [6] and analog front end [7] are being developed for data acquisition of the 11,520 input channels.…”

Section: Detector Overviewmentioning

confidence: 99%

Recent Progress on the GAPS Time of Flight System

Quinn¹

2019

Proceedings of 36th International Cosmic Ray Conference — PoS(ICRC2019)

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Fabrication of low-cost, large-area prototype Si(Li) detectors for the GAPS experiment

Cited by 31 publications

References 39 publications

Developing a mass-production model of large-area Si(Li) detectors with high operating temperatures

Developing a mass-production model of large-area Si(Li) detectors with high operating temperatures

Front-end Electronics for the GAPS Tracker

Recent Progress on the GAPS Time of Flight System

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