A search for anomalously heavy isotopes of low Z nuclei

We present preliminary results of a search for anomalously heavy isotopes of certain light elements using an electrostatic charged particle spectrometer in conjunction with the MP tandem accelerator facility at the Nuclear Structure Research Laboratory of the University of Rochester. New limits for the existence of anomalous, heavy isotopes (100–10,000 amu) in ordinary, terrestrial Li, Be, B and F samples and enriched H2, C13, and O18 samples are reported.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87394/2/1143_1.pd

The performance of "Virtual Phase" CCDs as detectors of minimum-ionizing particles

The Texas Instruments "Virtual Phase" CCD has been the basis of an ambitious design for a precision vertex detector to be used at the Stanford Linear Collider. The performance of this chip shows promise for future use in electron linear colliders. Experimental results are reported in addition to description of the electronic readout and preliminary mechanical design.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26549/1/0000088.pd

Design and operation of the Chicago air shower array

The Chicago Air Shower Array (CASA) is a large‐area surface scintillator array designed to study PeV sources of cosmic rays. The complete detector will consist of 1089 detector stations, distributed on a square 15 m grid. We have operated an array of 49 stations for much of the 1989 calendar year, an array of 529 stations for much of 1990, and the balance of the 1089 stations will be operating in early 1991. This surface array, together with the University of Michigan underground muon detectors (MIA), and the University of Utah atmospheric Čerenkov telescopes and Fly’s Eye air fluorescence detector, constitute a uniquely powerful instrument, dubbed the Utah Michigan Chicago (UMC) experiment, for the study of PeV sources. We report here the performance and current status of these detectors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87431/2/111_1.pd

Preliminary results from the Chicago air shower array and the Michigan muon array

The Chicago Air Shower Array (CASA) is a large area surface array designed to detect extensive air showers (EAS) produced by primaries with energy ∼100 TeV. It operates in coincidence with the underground Michigan Muon Array (MIA). Preliminary results are presented from a search for steady emission and daily emission from three astrophysical sources: Cygnus X‐3, Hercules X‐1, and the Crab nebula and pulsar. There is no evidence for a significant signal from any of these sources in the 1989 data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87432/2/122_1.pd

CASA‐MIA: A ‘‘precision’’ EAS detector

The CASA‐MIA detector was constructed to search for sources of UHE neutral radiation. As such it has established limits well below those of previously reported observations and of most contemporaneous detectors. In addition to its primary mission, however, CASA‐MIA measures the lateral distribution of both electrons and muons in EAS throughout a range of energies and with a degree of sampling not previously available.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87669/2/207_1.pd

Search for Ultra High Energy (UHE) γ-ray counterparts of BATSE 3B catalog events

We search for a Ultra High Energy (E>1014 eV)(E>1014eV) counterpart source to cosmic γ-ray bursts detected with the BATSE detectors. Using the 3B catalog positions, we examine 115 candidate bursts with the CASA-MIA detector for UHE γ-ray emission at or near the time of the observed γ-ray burst. No statistically significant excess of γ-rays is found from any of the candidate event regions. Based upon these results, we calculate the flux limits for UHE emission from these candidate event regions. Typical 95% confidence level flux limits are about 6×10−12 γ  cm−2 sec−16×10−12γcm−2sec−1 at a γ-ray detection threshold of 160 TeV. © 1996 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87368/2/598_1.pd

A search for diffuse gamma rays with energies above 1014 eV from molecular clouds in the galaxy

Diffuse gamma‐rays from molecular clouds are excellent tracers of cosmic rays in the galaxy over a wide range of energies. For example, diffuse emission detected by EGRET already places significant constraints on the spectrum and origin of galactic cosmic rays at GeV energies. Likewise, by measuring diffuse gamma rays with ground‐based air shower experiments, we can probe the galactic distribution of cosmic rays in the energy regime above 100 TeV.The Chicago Air Shower Array (CASA) which operates in coincidence with the Michigan muon array (MIA) is the world’s most sensitive experiment to gamma‐rays with energies ≳100 TeV, and is well‐suited for studies of diffuse sources based upon the muon content of air showers. We describe a search for diffuse gamma‐array emission from molecular cloud regions observed by CASA‐MIA. If we assume that the flux of cosmic rays is uniform in the galaxy, then we predict that diffuse emission will probably be detectable by CASA‐MIA within the lifetime of the experiment. Furthermore, if there are sources of cosmic rays in close proximity to certain molecular clouds, then the spectrum of gamma‐rays from these clouds will be stronger and harder. By searching for such enhancements in the diffuse emission, and by correlating the CASA‐MIA results with emission detected at lower energies by EGRET, we may identify or constrain the nature of cosmic rays sources in both energy regimes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87646/2/499_1.pd

A search for astrophysical point sources of 100 TeV gamma rays by the UMC collaboration

The CASA‐MIA experiment is a very large extensive air shower detector with good angular resolution. This instrument has been used to search the entire visible sky for astrophysical point sources of 100 TeV gamma rays. Approximately 90% of the isotropic charged cosmic ray background is rejected by measuring the muon content of the showers. Stringent limits are placed on the possible flux of 100 TeV sources across a large part of the Northern sky.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87711/2/1203_1.pd

A search for anomalously heavy isotopes of low Z nuclei

We present the results of a search for anomalously heavy isotopes of light elements using an electrostatic charged particle spectrometer in conjunction with the MP tandem accelerator facility at the Nuclear Structure Research Laboratory of the University of Rochester. New limits for the abundance of anomalously heavy isotopes (100-10000 amu) in ordinary terrestrial H, Li, Be, B, and F samples and enriched 2H, 13C, and 18O samples are reported.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26505/1/0000042.pd

An electrostatic beam line for accelerator mass spectroscopy of exotic particles

An all-electrostatic charged particle spectrometer has been constructed to perform high sensitivity searches for exotic states of matter. This spectrometer consists of an electrostatic beam line capable of mass independent charged particle transport and selection together with time-of-flight, energy loss and total energy detectors. This system has been used in conjunction with the tandem electrostatic accelerator at the Nuclear Structure Research Laboratory of the University of Rochester to search for fractionally charged or anomalously heavy particles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25663/1/0000215.pd