Three-dimensional position sensing and field shaping in orthogonal-strip germanium gamma-ray detectors

Amman, M.; Luke, P.N.

doi:10.1016/s0168-9002(00)00351-x

Cited by 109 publications

(60 citation statements)

References 22 publications

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“…Positioning in the third dimension is achieved directly by the time difference between the electron collection and the hole collection on opposite faces of the detector 18 . Amrose et al 19 showed that anode-cathode collection times provide a robust, nearly linear depth measurement.…”

Section: D Position-sensitive Germanium Detectors (3d-geds)mentioning

confidence: 99%

The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)

et al. 2012

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The balloon-borne Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS) instrument will provide a near-optimal combination of high-resolution imaging, spectroscopy, and polarimetry of solar-flare gamma-ray/hard X-ray emissions from ~20 keV to >~10 MeV. GRIPS will address questions raised by recent solar flare observations regarding particle acceleration and energy release, such as: What causes the spatial separation between energetic electrons producing hard X-rays and energetic ions producing gamma-ray lines? How anisotropic are the relativistic electrons, and why can they dominate in the corona? How do the compositions of accelerated and ambient material vary with space and time, and why? The spectrometer/polarimeter consists of sixteen 3D position-sensitive germanium detectors (3D-GeDs), where each energy deposition is individually recorded with an energy resolution of a few keV FWHM and a spatial resolution of <0.1 mm 3 . Imaging is accomplished by a single multi-pitch rotating modulator (MPRM), a 2.5-cm thick tungstenalloy slit/slat grid with pitches that range quasi-continuously from 1 to 13 mm. The MPRM is situated 8 meters from the spectrometer to provide excellent image quality and unparalleled angular resolution at gamma-ray energies (12.5 arcsec FWHM), sufficient to separate 2.2 MeV footpoint sources for almost all flares. Polarimetry is accomplished by analyzing the anisotropy of reconstructed Compton scattering in the 3D-GeDs (i.e., as an active scatterer), with an estimated minimum detectable polarization of a few percent at 150-650 keV in an X-class flare. GRIPS is scheduled for a continental-US engineering test flight in fall 2013, followed by long or ultra-long duration balloon flights in Antarctica.

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Section: D Position-sensitive Germanium Detectors (3d-geds)mentioning

confidence: 99%

The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)

et al. 2012

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“…Charge collection time determines the depth of the interaction, which allows for a full 3D position resolution to 1.6 mm 3 . A gap of 0.25 mm between the strips for the 2.0 mm pitch has been demonstrated by LBNL to minimize the number of charge sharing events and the resulting charge loss, while maintaining the high GeD spectral resolution [6]. Each detector is surrounded by a guard ring which is instrumented to provide veto signals.…”

Section: Instrument A) 3d Gedsmentioning

confidence: 99%

Overview of the Nuclear Compton Telescope

Perez-Becker¹

2009

Proceedings of 7th INTEGRAL Workshop — PoS(Integral08)

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The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and polarization. It consists of twelve high spectral resolution 3D Germanium strip detectors that track gamma-ray Compton scatter interactions with a resolution better than 2 mm 3 . Tracking technologies together with NCT's ultra-compact design provide dramatic improvements in Compton efficiency and sensitivity, achieving a similar effective area to COMPTEL with less than 1% of the detector volume. NCT will be breaking new ground in the measurement of polarized gamma-ray emission from astrophysical sources, while simultaneously providing a testing platform for novel event analysis, background reduction, and imaging techniques. Thus NCT is also serving as technology demonstration testbed for modern Compton telescopes, such as the Advanced Compton Telescope, or a focal plane detector of a gamma-ray focusing telescope. The instrument is currently being prepared for a 36-hour flight from New Mexico in Spring of 2009, followed by a long duration flight from Australia. On these science flights, NCT will map the Galactic positron annihilation, 26 Al, and 60 Fe emission, and perform a discovery study of polarization from all classes of gammaray sources. We present an overview of the NCT instrument, the planned flight program, and preliminary results of calibration and performance tests. 7th INTEGRAL Workshop

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“…14,15 The position detection in the lateral dimensions of x and y is accomplished using the conventional method for orthogonal-strip electrode geometries. To see how this is done, consider a gamma-ray interaction event taking place near the center of the detector.…”

Section: Position Sensingmentioning

confidence: 99%

“…With our detectors, we have studied the position measurement of the gamma-ray interaction events in all three dimensions rather than just two. 14,15 The depth of interaction in these detectors is obtained from the difference in the arrival time of the holes at an electrode on one side of the detector and that of the electrons at an electrode on the opposing detector surface. This separate detection of the hole collection and the electron collection is fundamental to the technique and is aided by the small-electrode charge collection properties [16][17][18] achieved with the strip electrodes.…”

Section: Introductionmentioning

confidence: 99%

<title>Position-sensitive germanium detectors for gamma-ray imaging and spectroscopy</title>

Amman

Luke

2000

Hard X-Ray, Gamma-Ray, and Neutron Detector Physics II

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Gamma-ray imaging with position-sensitive germanium detectors offers the advantages of excellent energy resolution, high detection efficiency, and potentially good spatial resolution. The development of the amorphous-semiconductor electrical contact technology for germanium detectors has simplified the production of these position-sensitive detectors and has made possible the use of unique detection schemes and detector geometries. We have fabricated prototype orthogonal-strip detectors for gamma-ray imaging studies using this contact technology. With these detectors, we demonstrate that a gamma-ray interaction event in the detector can be located in three dimensions. This more accurate determination of the interaction event position should ultimately lead to better image resolution. We have also taken advantage of the bipolar blocking nature of the amorphous-semiconductor contacts in order to investigate the use of fieldshaping electrodes. The addition of such electrodes is shown to improve the spectroscopic performance of the detectors by substantially eliminating charge collection to the inter-electrode surfaces. In addition, we demonstrate that this incomplete charge collection process can also be reduced by adjusting the properties of the amorphous-semiconductor layer. In this paper, we summarize the development of these position-sensitive detectors and present the results of our studies with the detectors.

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Three-dimensional position sensing and field shaping in orthogonal-strip germanium gamma-ray detectors

Cited by 109 publications

References 22 publications

The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)

The Gamma-Ray Imager/Polarimeter for Solar flares (GRIPS)

Overview of the Nuclear Compton Telescope

<title>Position-sensitive germanium detectors for gamma-ray imaging and spectroscopy</title>

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