615 research outputs found
Development of Thick-foil and Fine-pitch GEMs with a Laser Etching Technique
We have produced thick-foil and fine-pitch gas electron multipliers (GEMs)
using a laser etching technique. To improve production yield we have employed a
new material, Liquid Crystal Polymer, instead of polyimide as an insulator
layer. The effective gain of the thick-foil GEM with a hole pitch of 140 um, a
hole diameter of 70 um, and a thickness of 100 um reached a value of 10^4 at an
applied voltage of 720 V. The measured effective gain of the thick-foil and
fine-pitch GEM (80 um pitch, 40 um diameter, and 100 um thick) was similar to
that of the thick-foil GEM. The gain stability was measured for the thick-foil
and fine-pitch GEM, showing no significant increase or decrease as a function
of elapsed time from applying the high voltage. The gain stability over 3 h of
operation was about 0.5%. Gain mapping across the GEM showed a good uniformity
with a standard deviation of about 4%. The distribution of hole diameters
across the GEM was homogeneous with a standard deviation of about 3%. There was
no clear correlation between the gain and hole diameter maps.Comment: 21 pages, 9 figure
Kiso observations for 20 GRBs in HETE-2 era
We have established a GRB follow-up observation system at Kiso observatory
(Japan) in 2001. Since the east Asian area had been blank for the GRB follow-up
observational network, this observational system is very important in studying
the temporal and spectral evolution of early afterglows. Using this system, we
have performed quick observations for optical afterglows from early phase based
on HETE-2 and INTEGRAL alerts. Thanks to the quick follow-up observation
system, we have been able to use the Kiso observatory in 20 events, and conduct
their follow-up observations in optical and near infrared wavelengths.Comment: 5 pages, 4 figure. Accepted for publication into "il nuovo cimento".
Proceeding of the 4th Rome GRB conference, eds. L. Piro, L. Amati, S. Covino,
B. Gendr
Early (0.3 day) R-band light curve of the optical afterglow of GRB030329
We observed the optical afterglow of the bright gamma-ray burst GRB030329 on
the nights of 2003 March 29, using the Kiso observatory (the University of
Tokyo) 1.05 m Schmidt telescope. Data were taken from March 29 13:21:26 UT to
17:43:16 (0.072 to 0.253 days after the burst), using an -band filter. The
obtained -band light curve has been fitted successfully by a single power
law function with decay index of . These results remain
unchanged when incorporating two early photometric data points at 0.065 and
0.073 days, reported by Price et al.(2003) using the SSO 40 inch telescope, and
further including RTT150 data (Burenin et al. 2003) covering at about 0.3 days.
Over the period of 0.065-0.285 days after the burst, any deviation from the
power-law decay is smaller than 0.007 mag. The temporal structure reported
by Uemura et al. (2003) does not show up in our -band light curve.Comment: 9 pages, 2 figures, 1 table, accepted for publication in ApJ
A Suborbital Payload for Soft X-ray Spectroscopy of Extended Sources
We present a suborbital rocket payload capable of performing soft X-ray
spectroscopy on extended sources. The payload can reach resolutions of
~100(lambda/dlambda) over sources as large as 3.25 degrees in diameter in the
17-107 angstrom bandpass. This permits analysis of the overall energy balance
of nearby supernova remnants and the detailed nature of the diffuse soft X-ray
background. The main components of the instrument are: wire grid collimators,
off-plane grating arrays and gaseous electron multiplier detectors. This
payload is adaptable to longer duration orbital rockets given its comparatively
simple pointing and telemetry requirements and an abundance of potential
science targets.Comment: Accepted to Experimental Astronomy, 12 pages plus 1 table and 17
figure
WIDGET: System Performance and GRB Prompt Optical Observations
The WIDeField telescope for Gamma-ray burst Early Timing (WIDGET) is used for
a fully automated, ultra-wide-field survey aimed at detecting the prompt
optical emission associated with Gamma-ray Bursts (GRBs). WIDGET surveys the
HETE-2 and Swift/BAT pointing directions covering a total field of view of 62
degree x 62 degree every 10 secounds using an unfiltered system. This
monitoring survey allows exploration of the optical emission before the
gamma-ray trigger. The unfiltered magnitude is well converted to the SDSS r'
system at a 0.1 mag level. Since 2004, WIDGET has made a total of ten
simultaneous and one pre-trigger GRB observations. The efficiency of
synchronized observation with HETE-2 is four times better than that of Swift.
There has been no bright optical emission similar to that from GRB 080319B. The
statistical analysis implies that GRB080319B is a rare event. This paper
summarizes the design and operation of the WIDGET system and the simultaneous
GRB observations obtained with this instrument.Comment: 19 pages, 11 figures, Accepted to appear in PAS
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