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Results from GROCSE I: A real-time search for gamma ray burst optical counterparts

Description: The GROCSE I experiment (Gamma-Ray Optical Counterpart Search Experiment) is a rapid slewing wide field of view optical telescope at Lawrence Livermore National Laboratory which responds to triggers from the BATSE GRB data telemetry stream that have been processed and distributed by the BACODINE network. GROCSE 1 has been in continuous automated operation since January 1994. As of October 1995, sky images for 22 GRB triggers have been recorded, in some cases while the burst was still emitting gamma rays. The preliminary analysis of eight of these events are presented here. No optical counterparts have yet been detected. Limits for optical emission are given.
Date: October 27, 1995
Creator: Lee, B.; Akerlof, C. & Ables, E.
Partner: UNT Libraries Government Documents Department

An 800-MeV proton radiography facility for dynamic experiments

Description: The capability has been successfully developed at the Los Alamos Nuclear Science Center (LANSCE) to utilize a spatially and temporally prepared 800-MeV proton beam to produce proton radiographs. A series of proton bursts are transmitted through a dynamically varying object and transported, via a unique magnetic lens system, to an image plane. The magnetic lens system permits correcting for the effects of multiple coulomb scattering which would otherwise completely blur the spatially transmitted information at the image plane. The proton radiographs are recorded on either a time integrating film plate or with a recently developed multi-frame electronic imaging camera system. The latter technique permits obtaining a time dependent series of proton radiographs with time intervals (modulo 358 ns) up to many microseconds and variable time intervals between images. One electronically shuttered, intensified, CCD camera is required per image. These cameras can detect single protons interacting with a scintillating fiber optic array in the image plane but also have a dynamic range which permits recording radiographs with better than 5% statistics for observation of detailed density variations in the object. A number of tests have been carried out to characterize the quality of the proton radiography system for absolute mass determination, resolution, and dynamic range. Initial dynamic experiments characterized the temporal and spatial behavior of shock propagation in high explosives with up to six images per experiment. Based on experience with the prototype system, a number of upgrades are being implemented including the anticipated capability for enhanced mass discrimination through differential multiple coulomb scattering radiographs and more images with improved imaging techniques.
Date: December 1, 1998
Creator: King, N.S.P.; Adams, K. & Ables, E.
Partner: UNT Libraries Government Documents Department

Gamma Ray Burst Optical Counterpart Search Experiment (GROCSE)

Description: GROCSE (Gamma-Ray Optical Counterpart Search Experiments) is a system of automated telescopes that search for simultaneous optical activity associated with gamma ray bursts in response to real-time burst notifications provided by the BATSE/BACODINE network. The first generation system, GROCSE 1, is sensitive down to Mv {approximately} 8.5 and requires an average of 12 seconds to obtain the first images of the gamma ray burst error box defined by the BACODINE trigger. The collaboration is now constructing a second generation system which has a 4 second slewing time and can reach Mv {approximately} 14 with a 5 second exposure. GROCSE 2 consists of 4 cameras on a single mount. Each camera views the night sky through a commercial Canon lens (f/1.8, focal length 200 mm) and utilizes a 2K x 2K Loral CCD. Light weight and low noise custom readout electronics were designed and fabricated for these CCDs. The total field of view of the 4 cameras is 17.6 x 17.6 {degree}. GROCSE II will be operated by the end of 1995. In this paper, the authors present an overview of the GROCSE system and the results of measurements with a GROCSE 2 prototype unit.
Date: October 27, 1995
Creator: Park, H.S.; Ables, E. & Bionta, R.M.
Partner: UNT Libraries Government Documents Department

Beam control and diagnostic functions in the NIF transport spatial filter

Description: Beam control and diagnostic systems are required to align the National Ignition Facility (NIF) laser prior to a shot as well as to provide diagnostics on 192 beam lines at shot time. A design that allows each beam`s large spatial filter lenses to also serve as objective lenses for beam control and diagnostic sensor packages helps to accomplish the task at a reasonable cost. However, this approach also causes a high concentration of small optics near the pinhole plane of the transport spatial filter (TSF) at the output of each beam. This paper describes the optomechanical design in and near the central vacuum vessel of the TSF.
Date: October 1, 1996
Creator: Holdener, F.R.; Ables, E. & Bliss, E.S.
Partner: UNT Libraries Government Documents Department

First year results from LOTIS

Description: LOTIS (Livermore Optical Transient Imaging System) is a gamma-ray burst optical couterpart search experiment located near Lawrence Livermore National Laboratory in California. The system is linked to the GCN (GRB Coordinates Network) real-time coordinate distribution network and can respond to a burst trigger in 6-15 seconds. LOTIS has a total field-of-view of 17.4 degrees x 17.4 degrees with a completeness sensitivity of mv {approximately} 11 for a 10 second integration time. Since operations began in October 1996, LOTIS has responded to over 30 GCN/BATSE GRB triggers. Seven of these triggers are considered good events subject to the criteria of clear weather conditions, {lt}60 S RESPONSE TIME, AND {gt}50% coverage of the final BATSE 3(sigma) error circle. We discuss results from the first year of LOTIS operations with an emphasis on the observations and analysis of GRB 971006 (BATSE trigger 6414).
Date: November 17, 1997
Creator: Williams, G.G.; Parks, H.S. & Ables, E.
Partner: UNT Libraries Government Documents Department

Super LOTIS a high sensitive optical counterpart search experiment

Description: We are constructing a 0.6 meter telescope system to search for early time gamma-ray burst (GRB) optical counterparts. Super-LOTIS (Super-Livermore Optical Transient Imaging System) is an automated telescope system that has a 0.8 x 0.8{degree} field-of-view, is sensitive to M{sub v} {approximately} 19 and responds to a burst trigger within 5 min. This telescope will record images of the gamma-ray burst coordinates that is given by the GCN (GRB Coordinate Network). A measurement of GRB light curves at early times will greatly enhance our understanding of GRB physics.
Date: November 17, 1997
Creator: Park, H.S., Ables, E. & Band, D.L
Partner: UNT Libraries Government Documents Department

ABS plastic RPCs

Description: After investigating a number of materials, we discovered that an ABS plastic doped with a conducting polymer performs well as the resistive electrode in a narrow gap RPC (resistive plate chamber). Operating in the streamer mode, we find efficiencies of 90-96% with low noise and low strip multiplicities. We have also studied a variety of operating gases and found that a mixture containing SF{sub 6}, a non-ozone depleting gas, argon and isobutane gives good streamer mode performance, even with isobutane concentrations of 20% or less.
Date: February 1, 1996
Creator: Ables, E.; Bionta, R.; Olson, H.; Ott, L.; Parker, E.; Wright, D. et al.
Partner: UNT Libraries Government Documents Department

Fabrication of Cryogenic Manganite Bolometers to Measure the Total Energy at the LCLS Free Electron X-ray Laser

Description: We are developing cryogenic bolometers to measure the total energy of the Linac Coherent Light Source (LCLS) free electron X-ray laser that is currently being built at the Stanford Linear Accelerator Center. LCLS will produce ultrashort {approx}200 fs X-ray laser pulses with {approx}10{sup 13} photons at 0.8 keV up to {approx}10{sup 12} photons at 8 keV per pulse at a repeat interval as short as 8 ms, and will be accompanied by a halo of spontaneous undulator radiation. Our bolometer consists of a 375 {micro}m thick Si absorber and a Nd{sub 0.67}Sr{sub 0.33}MnO{sub 3} sensor operated at its metal-insulator transition. It will measure the total energy of each pulse with a precision of <1%, and is designed to meet the conflicting requirements of radiation hardness, sensitivity, linearity over a dynamic range of three orders of magnitude, and readout speed compatible with the LCLS pulse rate. Here we discuss bolometer design and fabrication, and the photoresponse of prototype devices to pulsed optical lasers.
Date: June 14, 2008
Creator: Drury, O B; Yong, G J; Kolagani, R M; Liang, Y; Gardner, C; Ables, E et al.
Partner: UNT Libraries Government Documents Department

Instrumentation of LOTIS: Livermore Optical Transient Imaging System; a fully automated wide field of view telescope system searching for simultaneous optical counterparts of gamma ray bursts

Description: LOTIS is a rapidly slewing wide-field-of-view telescope which was designed and constructed to search for simultaneous gamma-ray burst (GRB) optical counterparts. This experiment requires a rapidly slewing ({lt} 10 sec), wide-field-of-view ({gt} 15{degrees}), automatic and dedicated telescope. LOTIS utilizes commercial tele-photo lenses and custom 2048 x 2048 CCD cameras to view a 17.6 x 17.6{degrees} field of view. It can point to any part of the sky within 5 sec and is fully automated. It is connected via Internet socket to the GRB coordinate distribution network which analyzes telemetry from the satellite and delivers GRB coordinate information in real-time. LOTIS started routine operation in Oct. 1996. In the idle time between GRB triggers, LOTIS systematically surveys the entire available sky every night for new optical transients. This paper will describe the system design and performance.
Date: March 6, 1998
Creator: Park, H.S.; Ables, E.; Barthelmy, S.D.; Bionta, R.M.; Ott, L.L.; Parker, E.L. et al.
Partner: UNT Libraries Government Documents Department

An electro-optical imaging approach to the prompt signal processing problem of mega-channel SSC detector arrays

Description: The physics demands of high luminosity at the SSC and the sometimes subtle measurements required to elucidate new physics will undoubtedly tax existing instrumentation. As is the case with most experimental fields, new physics follows from better measurement concepts and technologies. We expect this to be the case with the SSC as well. In what follows, we offer a glimpse of what may be possible using some of the recent results from the emerging technologies in the field of electro-optics. 12 refs., 4 figs.
Date: December 1, 1990
Creator: Lowry, M.; Ables, E.; Bionta, R.; Haigh, R.; Hugenberg, K.; Kalibjian, R. et al.
Partner: UNT Libraries Government Documents Department