A high-resolution Ge spectrometer for Gamma-Ray burst astronomy

Owens, A.; Baker, R.; Cline, T. L.; Gehrels, N.; Jermakian, J.; Nolan, Thomas; Ramaty, R.; Seifert, H.; Shephard, D. A.; Smith, Gary R.; Stilwell, D. E.; Teegarden, B. J.; Cork, C.; Landis, D.A.; Luke, P.N.; Madden, N.; Malone, D.; Pehl, Richard H.; Yaver, H.; Hurley, K.; Mathias, Stefan; Post, A.

doi:10.1007/bf00751333

Cited by 22 publications

(18 citation statements)

References 19 publications

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“…The TGRS detector has been described by Owens et al (1995); our mass model is a modified version of the TGRS mass model used by Weidenspointner et al (2005) for their detailed instrumental background study. A section of the MAX-TGRS detector mass model, including the top of the tower, is depicted in Fig.…”

Section: Instrument and Spacecraft Modelsmentioning

confidence: 99%

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

Weidenspointner¹,

Wunderer²,

Barrière³

et al. 2006

Focusing Telescopes in Nuclear Astrophysics

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Abstract. MAX is a proposed Laue lens gamma-ray telescope taking advantage of Bragg diffraction in crystals to concentrate incident photons onto a distant detector. The Laue lens and the detector are carried by two separate satellites flying in formation. Significant effort is being devoted to studying different types of crystals that may be suitable for focusing gamma rays in two 100 keV wide energy bands centered on two lines which constitute the prime astrophysical interest of the MAX mission: the 511 keV positron annihilation line, and the broadened 847 keV line from the decay of 56 Co copiously produced in Type Ia supernovae. However, to optimize the performance of MAX, it is also necessary to optimize the detector used to collect the source photons concentrated by the lens. We address this need by applying proven Monte Carlo and event reconstruction packages to predict the performance of MAX for three different Ge detector concepts: a standard coaxial detector, a stack of segmented detectors, and a Compton camera consisting of a stack of strip detectors. Each of these exhibits distinct advantages and disadvantages regarding fundamental instrumental characteristics such as detection efficiency or background rejection, which ultimately determine achievable sensitivities. We conclude that the Compton camera is the most promising detector for MAX in particular, and for Laue lens gamma-ray telecopes in general.

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Section: Instrument and Spacecraft Modelsmentioning

confidence: 99%

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

Weidenspointner¹,

Wunderer²,

Barrière³

et al. 2006

Focusing Telescopes in Nuclear Astrophysics

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“…The occulter subtends 90¡ along the ecliptic plane,8 as seen from the detector, the width of the band thereby occulted being 16¡ FWHM at around 500 keV. Owens et al (1995) reported the results of extensive Monte Carlo simulations of the instrument response as a function of energy and zenith angle. The actual cross section of 35 cm2 is customarily reduced to an "" e †ective ÏÏ area by factoring in the efficiency of detection at a given energy and angle.…”

Section: Instrument and Detectormentioning

confidence: 99%

“…Our analysis therefore only uses photons that undergo full energy loss (where in any case the Ge response as a function of energy loss is maximal), i.e., that appear in the channel(s) at the nominal line energy and are referred to as the "" photopeak.ÏÏ In these terms, the photopeak e †ective area of the TGRS detector is^15 cm2 at 478 keV and zenith angle 0¡. It falls sharply with increasing energy but does not vary much with zenith angle (Owens et al 1995). The instrument response was operationally veriÐed by on-orbit comparisons of c-ray burst spectra with those obtained by CGRO/BATSE and W ind/Konus (Palmer et al 1996).…”

Section: Instrument and Detectormentioning

confidence: 99%

Transient Gamma‐Ray Spectrometer Observations of Gamma‐Ray Lines from Novae. III. The 478 keV Line from⁷Be Decay

Harris

Teegarden

Weidenspointner

et al. 2001

ApJ

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The W ind spacecraft, which carries the Transient Gamma Ray Spectrometer (TGRS), moves in an extremely elliptical orbit that largely avoids EarthÏs trapped radiation belts and albedo c-radiation. The TGRS therefore enjoys a relatively low level of background, which is also extremely stable. We show how this stability enables modeling of the time variability of background lines, which in turn enables a novel technique of background subtraction for use in the detection of transient astrophysical lines. We apply a simple version of this method to the line at 478 keV that is expected to arise from nucleosynthesis of 7Be in nearby novae. This search covers the entire southern ecliptic hemisphere during 1995È1997, including Ðve known individual events and possible undiscovered individual events. The TGRS design also uses W indÏs 3 s rotation period to modulate signals from the Galactic center. We use this feature of the instrument to search for a quasi-constant level of 478 keV emission from the accumulation of 7Be from several novae that are expected to occur in the direction of the Galactic center during that isotopeÏs 53 day half-life. We derive upper limits on the transient (single nova) emission that improve on previous limits by about an order of magnitude and limits on the steady (many nova) emission that represent a factor of 2 improvement. Only weak limits can be placed on the key parameters in the nucleosynthesis and ejection of 7Be, however.

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“…Observed count spectra, in units of counts per channel versus channel, were taken as indicative of incident photon spectra, except for a linear channel to energy conversion. Owens et al 1995. TGRS has observed hundreds of transient gamma-ray events, including solar outbursts, soft gamma repeaters, and gamma-ray bursts. This instrument was launched in 1994 November aboard the W ind spacecraft.…”

Section: Instrument Summarymentioning

confidence: 99%

“…The uncollimated detector contains a 6.7 cm diameter by 6.1 cm long germanium crystal and views the entire southern ecliptic hemisphere. Further details on the instrument design can be found in Owens et al (1995). The Russian Konus experiment is also on board the W ind spacecraft.…”

Section: Instrument Summarymentioning

confidence: 99%

High‐Resolution Spectroscopy of Gamma‐Ray Bursts with the Transient Gamma‐Ray Spectrometer

Kurczynski

Palmer

Seifert

et al. 2000

ApJ

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A search for spectral lines in gamma-ray bursts detected with the Transient Gamma-Ray Spectrometer has been unable to conÐrm their existence. The spectrometer, aboard the W ind spacecraft, has detected gamma-ray bursts and other transients since 1995. We have performed a systematic search for narrow spectral lines in gamma-ray bursts detected with this instrument that augments and extends the results of a similar search of bursts detected with BATSE. This search procedure tests for statistically signiÐcant lines at all possible times and durations during a burst using the method of maximum likelihood and C-statistic. Simulations demonstrated the e †ectiveness of this procedure, particularly on Poisson distributed data, for distinguishing real features from statistical Ñuctuations. The most promising line candidates were consistent with chance Ñuctuations, given the large number of spectra searched.

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A high-resolution Ge spectrometer for Gamma-Ray burst astronomy

Cited by 22 publications

References 19 publications

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

Transient Gamma‐Ray Spectrometer Observations of Gamma‐Ray Lines from Novae. III. The 478 keV Line from⁷Be Decay

High‐Resolution Spectroscopy of Gamma‐Ray Bursts with the Transient Gamma‐Ray Spectrometer

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A high-resolution Ge spectrometer for Gamma-Ray burst astronomy

Cited by 22 publications

References 19 publications

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

Monte Carlo study of detector concepts for the MAX Laue lens gamma-ray telescope

Transient Gamma‐Ray Spectrometer Observations of Gamma‐Ray Lines from Novae. III. The 478 keV Line from7Be Decay

High‐Resolution Spectroscopy of Gamma‐Ray Bursts with the Transient Gamma‐Ray Spectrometer

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Transient Gamma‐Ray Spectrometer Observations of Gamma‐Ray Lines from Novae. III. The 478 keV Line from⁷Be Decay