Gamma‐ray optical counterpart search experiment (GROCSE)

The requirements of a gamma‐ray burst optical counterpart detector are reviewed. By taking advantage of real‐time notification of bursts, new instruments can make sensitive searches while the gamma‐ray transient is still in progress. A wide field of view camera at Livermore National Laboratories has recently been adapted for detecting GRB optical counterparts to a limiting magnitude of 8. A more sensitive camera, capable of reaching mv=14, is under development. © 1994 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87629/2/633_1.pd

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

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 I 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 in progress. The preliminary analysis of eight of these events are presented here. No optical counterparts have yet been detected. Limits for optical emission are given. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87367/2/671_1.pd

Gamma ray burst optical counterpart search experiment (GROCSE)

GROCSE (Gamma-Ray Optical Counterpart Search Experiment) 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 I, is sensitive down to MV ∼ 8.5MV∼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 ∼ 14MV∼14 with a 5 second exposure. GROCSE II consists of 4 cameras on a single mount. Each camera views the night sky through a commercial Canon lens (f/1.8,(f/1.8, focal length 200 mm) and utilizes a 2K×2K2K×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 17.6×17.6°.17.6×17.6°. GROCSE II will be operating by the end of 1995. In this paper, we present an overview of the GROCSE system and the results of measurements with a GROCSE II prototype unit. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87369/2/861_1.pd

Neutrino astrophysics with IMB: past, present, and future

A burst of eight neutrino interactions occurring over a six second interval had been observed with the IMB detector. The closeness in time of the burst to the optical discovery of Supernova 1987a suggests that the neutrinos originated from stellar collapse. The characteristics of the burst are reviewed together with a recently completed reevaluation of many aspects of the detector's response. Efforts underway to discover past and future supernovae are also briefly discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27392/1/0000423.pd

The IMB photomultiplier test facility

An automatic system for testing up to 32 photomultiplier tubes (PMs) simultaneously under single photon counting conditions has been used to measure characteristics of more than 2500 PMs for use in the Irvine-Michigan-Brookhaven (IMB) proton decay experiment, 2048 tubes (64 EMI 9834B 8" diameter, and 1984 EMI 9870B 5" diameter) were selected for use in the 8000 m3 IMB water Cherenkov detector, now in operation for over a year. The PM test system is described and results of testing are presented along with PM performance in the IMB detector over the last year. In general, we find that the tube characteristics have smaller fluctuations than expected and that the tubes have proven to be reliable under rugged handling and operating conditions. On the basis of our experience, we make suggestions as to new industry standards for PMs to be used in particle counting.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25571/1/0000113.pd

IMB-3: a large water Cherenkov detector for nucleon decay and neutrino interactions

The IMB experiment, a large water Cherenkov detector which began data collection in September 1982, has undergone several upgrades to improve light collection, on-line processing power, data throughput and buffering, calibration, and operating efficiency. The current device, known as IMB-3, enjoys a factor of four light collection advantage over its precursor. Since May 1986, it has been used to search for such diverse phenomena as nucleon decay, dark matter, neutrino oscillation, and magnetic monopoles, and to study stellar collapse and cosmic rays. Due to its large size and long exposure time IMB presents unique challenges. The design and operation of the IMB-3 detector are described in detail.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31079/1/0000756.pd

Observation of strong electromagnetic fields around laser-entrance holes of ignition-scale hohlraums in inertial-confinement fusion experiments at the National Ignition Facility

Energy spectra and spectrally resolved one-dimensional fluence images of self-emitted charged-fusion products (14.7 MeV D[superscript 3]He protons) are routinely measured from indirectly driven inertial-confinement fusion (ICF) experiments utilizing ignition-scaled hohlraums at the National Ignition Facility (NIF). A striking and consistent feature of these images is that the fluence of protons leaving the ICF target in the direction of the hohlraum's laser entrance holes (LEHs) is very nonuniform spatially, in contrast to the very uniform fluence of protons leaving through the hohlraum equator. In addition, the measured nonuniformities are unpredictable, and vary greatly from shot to shot. These observations were made separately at the times of shock flash and of compression burn, indicating that the asymmetry persists even at ~0.5–2.5 ns after the laser has turned off. These phenomena have also been observed in experiments on the OMEGA laser facility with energy-scaled hohlraums, suggesting that the underlying physics is similar. Comprehensive data sets provide compelling evidence that the nonuniformities result from proton deflections due to strong spontaneous electromagnetic fields around the hohlraum LEHs. Although it has not yet been possible to uniquely determine whether the fields are magnetic (B) or electric (E), preliminary analysis indicates that the strength is ~1 MG if B fields or ~10[superscript 9] V cm[superscript −1] if E fields. These measurements provide important physics insight into the ongoing ignition experiments at the NIF. Understanding the generation, evolution, interaction and dissipation of the self-generated fields may help to answer many physics questions, such as why the electron temperatures measured in the LEH region are anomalously large, and may help to validate hydrodynamic models of plasma dynamics prior to plasma stagnation in the center of the hohlraum.United States. Dept. of Energy (DE-FG52-07 NA280 59)United States. Dept. of Energy (DE-FG03-03SF22691)Lawrence Livermore National Laboratory (B543881)Lawrence Livermore National Laboratory (LD RD-08-ER-062)University of Rochester. Fusion Science Center (412761-G)General Atomics (DE-AC52-06NA 27279)Stewardship Science Graduate Fellowship (DE-FC52-08NA28752

Experimental limits on monopole catalysis, N oscillations, and nucleon lifetimes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25877/1/0000440.pd

Experimental limits on nucleon decay and ΔB=2 processes

Results from the IMB collabration to detect possible proton decay in a salt mine near Cleveland, Ohio are presented. Detection apparatus is described.(AIP)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87900/2/1_1.pd