-
H. Tajima,
T. Nakamoto,
T. Tanaka,
S. Uno,
T. Mitani,
Ed.Ce. Silva,
Y. Fukazawa,
T. Kamae,
G. Madejski, D. Marlow,
K. Nakazawa,
M. Nomachi,
Y. Okada,
T. Takahashi
[show abstract]
[hide abstract]
ABSTRACT: Compton telescopes based on semiconductor technologies are being developed to explore the gamma-ray universe in an energy band 0.1-20 MeV, which is not well covered by the present or near-future gamma-ray telescopes. The key feature of such Compton telescopes is the high energy resolution that is crucial for high angular resolution and high background rejection capability. The energy resolution around 1 keV is required to approach physical limit of the angular resolution due to Doppler broadening. We have developed a low noise front-end ASIC (application-specific integrated circuit), VA32TA, to realize this goal for the readout of double-sided silicon strip detector (DSSD) and cadmium telluride (CdTe) pixel detector which are essential elements of the semiconductor Compton telescope. We report on the design and test results of the VA32TA. We have reached an energy resolution of 1.3 keV [full-width at half-maximum (FWHM)] for 60 and 122 keV at 0° C with a DSSD and 1.7 keV (FWHM) with a CdTe detector.
IEEE Transactions on Nuclear Science 07/2004; · 1.45 Impact Factor
-
H Tajima,
T Nakamoto,
T Tanaka,
S. Uno,
T Mitani,
E do Couto e Silva,
Y. Fukazawa,
T. Kamae,
G. Madejski, D. Marlow,
K Nakazawa,
M. Nomachi,
Y Okada,
T Takahashi
[show abstract]
[hide abstract]
ABSTRACT: Compton telescopes based on semiconductor technologies are being developed to explore the gamma-ray universe in an energy band 0.1-20 MeV, which is not well covered by the present or near-future gamma-ray telescopes. The key feature of such Compton telescopes is the high energy resolution that is crucial for high angular resolution and high background rejection capability. The energy resolution around 1 keV is required to approach physical limit of the angular resolution due to Doppler broadening. We have developed a low noise front-end ASIC, VA32TA, to realize this goal for the readout of Double-sided Silicon Strip Detector (DSSD) and Cadmium Telluride (CdTe) pixel detector which are essential elements of the semiconductor Compton telescope. We report on the design and test results of the VA32TA. We have reached an energy resolution of 1.3 keV (FWHM) for 60 keV and 122 keV at 0°C with a DSSD and 1.7 keV (FWHM) with a CdTe detector.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
-
R. BIanford,
P. Chen,
T. Kamae,
G. Madejski,
J. Ng,
T. Mizuno,
H. Tajima,
T. Thurston,
L. Barbier,
P. Bloser, [......],
J. Kataoka,
N. Kawai,
Y. Fukazawa,
P. Carlson,
W. Klamra,
M. Pearce,
C.-I. Bjornsson,
C. Fransson,
S. Larsson,
F. Ryde
[show abstract]
[hide abstract]
ABSTRACT: We are developing a new balloon-borne instrument (PoGO), to measure polarization of soft gamma rays (25-200 keV) using asymmetry in azimuth angle distribution of Compton scattering. PoGO will detect 10% polarization in 100mCrab sources in a 6-8 hour observation and bring a new dimension to studies on gamma ray emission/transportation mechanism in pulsars, AGNs, black hole binaries, and neutron star surface. The concept is an adaptation to polarization measurements of well-type phoswich counter technology used in balloon-borne experiments (Welcome-1) and AstroE2 Hard X-ray Detector. PoGO consists of close-packed array of 397 hexagonal well-type phoswich counters. Each unit is composed of a long thin tube (well) of slow plastic scintillator, a solid rod of fast plastic scintillator, and a short BGO at the base. A photomultiplier coupled to the end of the BGO detects light from all 3 scintillators. The rods with decay times < 10 ns, are used as the active elements; while the wells and BGOs, with decay times ∼ 250 ns are used as active anti-coincidence. The fast and slow signals are separated out electronically. When gamma rays entering the field-of-view (fwhm ∼3deg<sup>2</sup>) strike a fast scintillator, some are Compton scattered. A fraction of the scattered photons are absorbed in another rod (or undergo a second scatter). A valid event requires one clean fast signal of pulse-height compatible with photo-absorption (> 20 keV) and one or more compatible with Compton scattering (< 10 keV). Studies based on EGS4 (with polarization features) and Geant4 predict excellent background rejection and high sensitivity.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
