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We present the initial results of the first germanium strip detector array for the imaging and high-resolution spectroscopy of gamma-ray sources. The array consists of four detectors, 5 /spl times/ 5 /spl times/ 1 cm each, with 25 strips on each side. The detectors are daisy chained to hybrid preamplifiers to reduce the number of channels of electronics. Good spectroscopy and imaging are achieved. We also present results from the development of an amorphous germanium contact technology as an alternative to the lithium contact technology. A prototype 25 /spl times/ 25 strip detector was manufactured with this new technology and demonstrates good spectroscopy and imaging.

Three-dimensional optical random access memories (3D ORAMs) are a new generation of high-density data storage devices. Binary information is stored and retrieved via a light induced reversible transformation of an ensemble of bistable photochromic molecules embedded in a polymer matrix. This paper describes the application of 3D ORAM materials to radiation dosimetry. It is shown both theoretically and experimentally, that ionizing radiation in the form of heavy charged particles is capable of changing the information originally stored on the ORAM material. The magnitude and spatial distribution of these changes are used as a measure of the absorbed dose, particle type and energy. The effects of exposure on 3D ORAM materials have been investigated for a variety of particle types and energies, including protons, alpha particles and 12C ions. The exposed materials are observed to fluoresce when exposed to laser light. The intensity and the depth of the fluorescence is dependent on the type and energy of the particle to which the materials were exposed. It is shown that these effects can be modeled using Monte Carlo calculations. The model provides a better understanding of the properties of these materials. which should prove useful for developing systems for charged particle and neutron dosimetry/detector applications. c2001 Published by Elsevier Science B.V.

The status of pollution of the Arctic basin is studied in ecological terms, and the interactions of the Arctic ecosystem with the global system are estimated. A spatial simulation model for the kinetics of pollutants in the Arctic basin is proposed in which the ecological and spatial distribution of the hydrological parameters is taken into account. The model includes blocks describing the flows of pollutants in the trophic chains, the exchange between the water–ice system and the atmosphere and the interaction of the water ecosystem with the global biosphere–climate system. A global model controls the inputs of the simulation model and makes it possible to compute the dynamics of the distribution of pollutants between the Arctic aquatories, which include the Central basin and the peripheral seas. The model uses both published data and the data of the US/Russian expedition to Siberia accomplished in the summer of 1995. Climatic and anthropogenic processes are described in the form of scenarios. The results of computer experiments are given demonstrating the advantages of the simulation model to forecast and to estimate the dynamics of radionuclides, heavy metals and oil hydrocarbons in the Arctic Seas. The total and local pictures of the spatial distribution of pollutants in the Arctic basin are given as functions of various environmental and anthropogenic parameters. It is concluded that the use of the global biospheric model enables the consideration of the interactions between the Arctic basin environment and adjoining territories. This allows estimates to be made of the consequences of the anthropogenic impact on the Arctic ecosystem.

The first experimental investigation has been performed of radiation effects on three-dimensional optical random-access-memory materials. Thin films of poly(methyl methacrylate) doped with spirobenzopyran were irradiated with uniform fluxes of protons, α-particles and 12 C +3 ions, at fixed energies per nucleon from 0.5 to 2.5 MeV and fluences from 10 10 to 10 14 cm −2 . The exposed films were examined under a confocal laser scanning microscopy system which is capable of optically sectioning the materials. The irradiation resulted in a permanent change in the materials from a nonfluorescent form to a form which is fluorescent under both 488 and 514 nm excitation. Profiles were measured of fluorescent intensity versus depth, and of intensity versus dose. It was found that both the particle energy and the dose can be obtained from measuring the width of the depth profile and the fluorescent intensity. These properties are very promising for dosimetry applications since they allow calculation of an accurate dose equivalent.

A pilot program has been initiated at Kirtland AFB, New Mexico to study new methods of environmental characterization and restoration of sites contaminated with potential mixed wastes. The initial program studied four sites whose primary radioactive contaminant was thorium. Geophysical, nuclear, and chemical analyses were performed during the initial phase, with the program currently expanding to include biochemical studies. The entire program was conducted on-site to eliminate public health concerns about hazardous waste movement and to provide a more efficient and effective way to collect and process characterization samples. Chemical analyses showed no significant chemical contamination by metals, semi-volatile organic compounds, and total petroleum hydrocarbons by EPA standards and thus indicated that the soil would not have to be treated as mixed waste. Radioactivity analysis showed a 232 Th activity that ranged from background levels to over 1000 pCi/g. Additionally, using dry sieving, a correlation was found between sample radiation content and soil grain size. It is planned to exploit this effect later in the program when site remediation strategies are developed.

This paper considers the problem of the origin of the pollution level in the Yenisey river estuary which is located in north-central Siberia and empties into the Kara sea. In the framework of this problem, a joint American–Russian environmental and hydrophysical expedition to the Angara and Yenisey rivers of Siberia was accomplished in the summer of 1995. Using the results of the pollution measurements taken during this expedition, it becomes possible to begin the synthesis of the spatial mathematical model for pollution transport in the Angara–Yenisey river system. The model includes blocks describing the flows of pollutants from biogeochemical, hydrophysical and anthropogenic sources. The influence of soil–plant formations are considered. The model is designed for interactive use in the mode of a computer experiment. The results of model calculations and of the expedition are given.

In recent years, the world has learned about the dumping of nuclear reactors and other waste into the Arctic seas by the former Soviet Union. Most of the information on the present levels of radioactivity in the region has been obtained by oceanographic expeditions conducted during the brief Arctic summers. Year-round monitoring of the movement of radioactivity during dynamic seasonal and episodic chances is hampered by the difficulties caused by sea ice, logistics and communication constraints associated with deployment and maintenance of monitoring equipment in this remote region. We have designed an autonomous station to measure the benthic gamma-ray emitting radioactivity for periods of at least one year. The station is capable of detecting a 30 Bq/m/sup 3/ increase in the /sup 137/Cs activity in a 24 hour period. After a year-long deployment, the station releases its anchor and rises to the surface to transmit the accumulated spectra and oceanographic data via an Argos satellite link. The design and performance characteristics of the prototype station will be discussed.

Compton cameras use the kinematics of Compton scattering to construct a source image without the use of collimators or masks. Compton telescopes were first built in the 1970s for astronomical observations. The first laboratory instrument was designed for medical imaging. Recently, three dimensional imaging has been demonstrated using an array of high resolution germanium detectors for characterization of mixed radioactive waste containers. Image resolution depends on the detector accuracy in both energy and position and on the image reconstruction algorithm. Advantages of Compton imaging include a wide field of view, background suppression, the ability to image high energy gamma rays (up to 10 MeV) and the ability to obtain three dimensional images from a fixed position on one side of the source without the need for tomography. The operation of Compton cameras will be reviewed along with recent results and future prospects.

A Compton camera was constructed using four individual high-purity germanium (HPGe) coaxial detectors in the front plane and four elements of a 15 element HPGe coaxial array in the back plane. 60Co, 133Ba, and 137Cs sources were used in configurations that included single sources in positions covering the intended field-of-view and multiple sources of both identical isotopes and different isotopes. Experiments were also conducted with sources in waste-container sized attenuating media. This proof-of-concept experiment was designed to demonstrate non-tomographic three-dimensional imaging for the characterization of mixed waste containers. The present analysis demonstrates three-dimensional imaging of multiple sources at multiple energies and the imaging of sources within a waste-container sized attenuating medium.

Cosmic ray interactions with materials result in secondary neutrons which are easily measurable. The magnitude of this neutron flux depends on geomagnetic latitude, altitude, and on the materials that constitute the local environment. In general the neutrons produced by cosmic rays in a given object depend on the atomic number, density, and total mass of the elements which constitute that object. Any massive object will have a unique “neutron signature” depending on its materials and structure. To test if this phenomenon might be used to determine if a closed canister contains a specific object, such as a missile, we conducted a proof of concept study. The study had two parts, experimental and Monte Carlo simulations. The object was to perform measurements and simulations of a “block missile mockup”. We constructed the mockup at approximately one-sixth the mass of a real missile. A clear neutron signature was observed from this mockup experimentally, and modeling predictions agreed well with the data. Predictions from our results indicate that a full sized missile should produce a very distinct signature.

A proof-of-concept experiment was performed to demonstrate the three-dimensional imaging capabilities of an all-germanium Compton camera for near-field sources. Eight high purity germanium (HPGe) coaxial detectors were configured in two planes of four detectors each. The data acquisition system was assembled from available hardware and off-the-shelf electronics using standard NIM and CAMAC modules. Sixteen-parameter data were recorded event-by-event for later analysis and image reconstruction. The energy resolution of the system was 0.3% at 1333 keV. Preliminary analysis indicates the position resolution for a source at one meter and a specific detector geometry was less than a centimeter. >

In our previous work, a 1 mm thick 238U (uranium) disk backed by a charged-particle detector, when exposed to the neutron flux from a 252Cf (californium) source (mean neutron energy of 2.2 MeV), showed a count-rate increase that was higher than can be accounted for by the detection of short-range primary fission fragments. Electrons resulting from fission product decays were seen as a more plausible reaction mechanism. The current study extends the investigation of this phenomenon by using six 238U disks ranging in thickness from 100 μm to 1 mm in order to discern the relationship between disk thickness and neutron detection efficiency. Also considered is the effect of using thin foils of nonfissionable material in order to suppress the α-particle background from the 238U disks. The exact isotopic composition of these 238U samples is known, which eliminates a source of ambiguity in the previous study. With these samples we find that the excess neutrons found in the previous study are not seen. This forces us to conclude that the results reported in our previous work were not due to the detection of electrons resulting from β-decay of the fission products of 238U, but were most likely the result of the interaction of a neutron with an impurity in the previous samples.

The authors report the first complete gamma-ray survey of a large spacecraft, the Long Duration Exposure Facility (LDEF). The survey was conducted using an array of germanium detectors from the US Naval Research Laboratory and individual detectors from the Institute for Space Science and Technology to study the accumulation and distribution of radioisotopes induced in the wide variety of materials present on the LDEF. /sup 22/Na, /sup 7/Be, /sup 54/Mn/el, and the positron annihilation line were all strongly observed. Traces of /sup 56/Co, /sup 57/Co, and /sup 60/Co were also observed The most striking feature of the data was the unexpected distribution of /sup 7/Be, which was predominately present on the leading surfaces of the spacecraft. The evidence clearly indicates an accretion of the /sup 7/Be onto the surface of the LDEF. This is the first known observation of the deposition of a radioisotope onto the surface of a spacecraft. /sup 7/Be is a spallation product of cosmic rays on nitrogen and oxygen in the upper atmosphere. To explain the surface density of 5.4*10/sup 5/ atoms/cm/sup 2/, it must be assumed that the light /sup 7/Be atom is transported up from lower altitudes. >

The effects of exposure of 3D GRAM materials to protons, alphas and /sup 12/C ions have been investigated in the energy range of 0.5 to 2.5 MeV per nucleon. A permanent change occurs in the properties of the materials due to irradiation. The exposed materials are observed to fluoresce under a confocal laser scanning microscope. The intensity and depth of the fluorescence is dependent on the type and energy of the particles to which the materials were exposed. These properties should prove useful for charged particle and neutron dosimetry/detector applications.

The Radiation Detection Section of the Naval Research Laboratory (NRL) is sponsored by the Defense Nuclear Agency (DNA) to study the feasibility of using passive cosmic-ray induced neutron signatures as a method of treaty verification. The main thrust has been to use the neutron signature as a unique method for verification of the type of missile or other treaty limited item (TLI) inside a closed container. The detector for the experiments described consisted of nine /sup 3/He neutron proportional counter tubes that were three feet long and at a pressure of ten atmospheres. The object of the experiments was to use this neutron detector to measure the neutron signature of a semi-realistic mock-up of a generic missile. Clear variations in the neutron signal at different points over the mock-up are shown, demonstrating that measurable neutron signatures do exist. >

The paper investigates a mechanism that allows distributed programs to reduce their network usage by moving code segments between computers. The idea of moving code is developed into an abstract model of distributed computation called the Ship Model that has a basic entity called a ship. Ships contain code and data and are somewhat like objects that can migrate. The term 'ship' is used to emphasize its mobility. The Ship Model uses mobility both as a way of moving code and data between machines and as an inter-ship communication mechanism. A prototype implementation written in C and running under Unix is constructed with test machines connected either by a high speed Ethernet network or a slow speed dialup line. A few example applications are implemented and tested under the prototype. Various measurements show that the Ship Model can provide increased performance both in the high and lour speed settings. Various issues regarding the implementation of the Ship Model are also discussed. >

Compton imaging systems have a number of advantages for characterization of nuclear waste, such as identifying hot spots in mixed waste in order to reduce the volume of high-level waste requiring extensive treatment or long-term storage, and imaging large objects or contaminated areas. Compton imaging also has potential applications for monitoring production, deployment, shipping and storage of nuclear warheads and components in the verification of treaties such as START I and II, the Comprehensive Test Ban Treaty and the Non-Proliferation Treaty. This article presents a brief historical perspective and discusses system design requirements and performance specifications for these applications. The advantages of Compton imaging are compared to competing imaging technologies.

GaAs is a potentially attractive material for room temperature X-ray and /spl gamma/-ray spectrometers. To date, the only high resolution GaAs devices were produced by epitaxial growth. The usefulness of detectors made from bulk grown semi-insulating (SI) GaAs has been limited by low charge collection efficiency caused, it is believed, by the high density of EL2 deep donor defects. Vertical zone melt (VZM) growth of GaAs has recently been developed at the Naval Research Laboratory. Zone refining and zone leveling techniques were used with VZM to reduce the level of impurities and the EL2 defects in bulk SI-GaAs. Schottky barrier and PIN diodes have been fabricated from the newly grown material. These devices were characterized using /spl alpha/ particles and /spl gamma/-rays. In this paper, the measurements and analysis of the first VZM GaAs devices are presented and compared with commercially available GaAs. The intent is to test the hypothesis that high purity, low defect GaAs material growth could lead to improved radiation detectors.

Germanium detector systems with both high spectral resolution and good imaging capabilities to the problems of environmental remediation. Over the last year, much progress has been made. We have (1) developed and built amorphous-contact germanium detectors of increasing sophistication, (2) built and tested an array of four position sensitive germanium detectors, (3) demonstrated spectroscopy and imaging uses with 235U, and Results from this research were presented at the EMSP's first workshop in Chicago in 1998, at the SPIE Session in July 1999, and at the IEEE Nuclear Science Symposium in November 1998 and 1999. AMORPHOUS CONTACTS The goal of the amorphous contact effort was to extend the single element (pixel) amorphous technology developed by Luke et al. (1994) to double-sided orthogonal strip detectors. Amorphous contact provides multiple advantages over the current lithium contact technology. We have fabricated the first orthogonal strip detector with dimensions appropriate for field use. The detector has an active volume of 50 mm x 50 mm x 10 mm and has 25 x 25 strips (see Figure 1). It is currently undergoing tests. The resolution is {approx}12 keV FWHM, which is dominated by electronic noise. The noise was high because of the large capacitance and the non-optimal electronics used with the test cryostat.

Significant quantities of Be-7 have been found on the leading edge of the Long Duration Exposure Facility (LDEF), which was returned to earth after almost six years in space. Although the absolute atmospheric concentration of Be-7 needed to explain this detection is extremely small, its concentration at LDEF's altitude must be several orders of magnitude higher than in the stratosphere below, where it is produced by cosmic-ray reactions with atmospheric nitrogen and oxygen nuclei. The detection may lead to the use of Be-7 as an exoatmospheric tracer as well as to studies of surface interactions in space.

The goal of this project is the development of field portable gamma-ray detectors that can both image gamma rays from radioactive emission and determine the isotopic composition by the emitted spectrum. Most instruments to date have had either very good imaging with no spectroscopy, or very good spectroscopy with no imaging. The only instruments with both imaging and spectroscopy have had rather poor quality imaging and spectroscopy (e.g. NaI Anger Cameras). The technology would have widespread applications, from laboratory nuclear physics, to breast cancer imaging, to astronomical research. For this project, we focus on the applications in the field of fissile materials, spent nuclear fuels and decontamination and decommissioning.

'The objective of this research is the development of high resolution germanium detector systems for direct imaging of spent nuclear fuels and fissile materials and Compton scatter imaging of large objects of arbitrary size. A small configuration of detectors shall be assembled to demonstrate the performance of such a system. The efforts in this first year of a three year program have been focused on the design and procurement of a four detector array of germanium strip detectors. The basic detector is a 5 cm x 5 cm x 1 cm thick planar germanium detector with segmented anode and cathode. These segmentations are in the form of strips with a pitch of 2 millimeters. The strips on the anode side run orthogonal to the strips on the cathode side so that, in a gamma-ray interaction, the collection of electrons and holes on opposite electrodes produces signals which identify the interaction position in two dimensions. Each detector in the array has 25 anode contacts and 25 cathode contacts. The detector array has been designed as a planar array providing 100 square centimeters of active area mounted in a single cryostat. To reduce electronics channel count, parallel strips from adjacent detectors are electrically joined together effectively making strips that are 10 cm long. In this configuration, 100 channels of electronics are required to readout the array. In a related project, the authors are investigating processes to produce improved contacts for germanium strip detectors which would offer both more reliable extended use and the potential for finer strip pitch or position resolution. Investigating amorphous contacts, they have, to date, prepared two Ge test detectors. One was produced using n-type Ge and the other p-type Ge. The p-type detector has a Li diffused contact on one side while the n-type detector has a B ion-implanted contact. Amorphous contacts have been formed on the opposite side of each detector by RF sputtering. They are currently conducting a series of leakage current versus operating temperature measurements in order to determine the barrier heights of the amorphous contacts. The use of n and p type detectors will allow us to measure the electron and hole blocking behavior of the contacts respectively. This will provide important information on the nature of these contacts and will determine if double-sided strip detectors can be produced using only amorphous contacts.'

Currently, the detection of ambient levels of tritium in the atmosphere using beta decay techniques is limited by the need for large sample volumes and long sampling and processing times. Accelerator mass spectrometry (AMS) can significantly reduce both the counting time and the sample size in tritium measurements. Using the Crocker Nuclear Laboratory (CNL) cyclotron we have achieved an efficiency of 1.8 × 10−5 with a T/H ratio of 2.2 × 10−13 using a sample size of 32 mBq (0.85 pCi). Counting times were between 4 to 6 min. An analysis of the current results as well as future improvements will be discussed. The current research demonstrates the great potential for a dedicated, monoenergetic, low energy AMS system to meet the needs of low-level tritium detection.

A rugged HPGe detector capable of taking high resolution data in a vibrational environment has been developed. The objectives included a detector with 35% gamma efficiency and 1.90 keV energy resolution (both quantities measured at 1332.5 keV), a dewar with a capacity of 1.2 l and a hold time of 24 h. Results of vibration tests performed on large HPGe detectors hard mounted on a shake table were used to guide detector modifications in this program. Severe resonances were found in the low frequency region for transverse vibrations for commercial hand-held detectors. These were eliminated in a redesigned rugged detector with a stiffened dewar and a solid cold finger. This detector with a further improved dewar has a hold time of nearly 40 h and a better performance in a vibrational environment. To fabricate rugged detectors, crucial components in the dewar-cryostat arrangement must be stiffened and all components mounted securely.

A prototype electronics package of amplifier, ADC, pulser, data-bus interface, bias supply and low voltage supply has been developed to process high resolution data from rugged intrinsic germanium detectors with high reliability in a harsh environment. This sturdy modular package attachable to the dewar of a rugged detector oriented horizontally or downward degrades detector energy resolution at 1332 KeV less than 0.25 KeV.

Commonly used least-squares fitting procedures can lead to strongly biased results when fitting peaks with very low statistics. The problem has been identified as being due to large statistical fluctuations in the data, leading to large variations in the weights used for the fit. Several modifications to the least-squares method are investigated for efficiency in eliminating the bias. These are tested on a set of gamma-ray spectra constructed in the laboratory and variously summed so as to give results with statistics increasing from very low to good. Three-point averaging or five-point smoothing of the data for calculating the weights are found to give consistent, unbiased results on these data. Other modifications of the least-squares method are shown to give less satisfactory results. When applicable, a simple “hand analysis” gives more consistent results than any of the fitting methods.

A review is given of techniques for the complete automatic analysis of multichannel gamma-ray spectra from high-resolution germanium detectors, and a FORTRAN computer program is described. Previously reported fitting methods, peak shape functions, and peak search techniques are discussed. A semi-empirical peak shape is presented which gives a good fit to the variety of peak shapes and intensities which may be found in a spectrum. Equivalence is shown between a peak search using the covariance of a general peak shape with the data and a search using a general zero-area transform on the data. A comparison is made of the sensitivities of four different transforms when used in a peak search.

A study has been made of the efficiency of various techniques for use in the analysis of peaks in gamma spectra with very poor statistics. A comparison was made of the efficacy of variously shaped transforms used for smoothing and of four different zero-area transforms when used to search for very weak peaks. Results are given for computer generated data consisting of a peak on a flat background with added "random" noise. A related problem is the accurate analysis for area and position of peaks with only a few counts per channel. The standard least squares method failed to give a satisfactory fit. A simple technique is given for correcting this difficulty.

The detection of very low concentrations of tritium in the atmosphere requires rather large samples and counting times using conventional radioactive decay techniques. Substantial reductions in both sample size and counting time can be realized using accelerator mass spectrometry techniques. We have used the sector-focused cyclotron at the Naval Research Laboratory to detect tritium in hydrogen at the level of 1 part in 1012 in a 4 ml sample of hydrogen at 1 atm pressure and 15 min counting time. The detection techniques as well as improvements in beam transport efficiency and elimination of memory effects in the accelerator will be presented.

The peak-to-total ratio and absolute efficiency of a 5″ dia. × 5″ NaI crystal for gamma-ray energies from 0.4 to 9.2 MeV have been measured by using a magnetic spectrometer to isolate nuclear states which decay by only one gamma transition. Particle-gamma-ray coincidence measurements provide the pulse-height spectrum for a single gamma-ray energy. The detector efficiency is determined by detecting only those particles leading to the nuclear state which provides the desired gamma ray. The efficiency is given by the ratio of the coincidence counts in the gamma-ray spectrum to the particle counts in the spectrometer. The peak-to-total ratio data were supplemented by singles measurements from some gamma-ray sources and (p,γ) and (p,αγ) reactions.

An accelerator mass spectrometer (AMS) for direct atom counting of tritium has been developed using the Crocker Nuclear Laboratory's (CNL) 76-in sector-focused cyclotron. Tritons were accelerated to 6.2 MeV and detected in a silicon Delta E-E charged-particle telescope. A detection efficiency of 2.4*10/sup -5/ was achieved with the smallest sample detected, which contained 2.6 mBq (70 fCi) of tritium at a T/H ratio of 3.7*10/sup -13/. Counting times were 3 to 6 min, with smaller samples requiring less time. This technique greatly reduces counting times and sample sizes from that required in existing beta -decay detection of ambient levels of tritium. >

A fast approximation to the complementary error function has been programmed and tested for use in the peak-shape function for fitting peaks in gamma-ray spectra. The function was compared for speed and accuracy on the NRL ASC 7 computer to the mathematical library version of the complementary error function. The approximation has resulted in a 50% time savings in the computer program HYPERMET which was developed at NRL for automatic analysis of gamma-ray spectra from germanium detectors.

The γ-ray decay of neutron particle-hole states in 140 Ce has been studied with the reaction 140 Ce(p,p′γ o ) 140 Ce. Evidence is presented that the strong ground-state γ rays observed from some of these states are E1 transitions. This allows the identification of 1 − states.

Proton resonance structure was observed in the 205Tl(d, p) reaction at single-particle energies for out-going protons leading to all strongly excited states below 3 MeV excitation in 206Tl. Decay of the isobaric analog of the 207Tl ground state was not observed.

Symptoms associated with one unit of solution of posterior pituitary extract given intravenously occur frequently but are transient, variable, and do not contraindicate the use of the drug. Injections have been given to thousands of patients and only one in over 28 years was found to be unusually susceptible, and while she was sick for several hours, she was never critically ill. She also consented to two subsequent studies. Death is usually due to hemorrhage and shock from the ruptured uterus following the injection of from 5 to 10 units of the pituitary solution. There are numerous subjective symptoms in postpartum patients receiving oxytocic medication intravenously. In 2 groups of patients totaling 37 who received intravenous injections of ergonovine maleate 0.4 mg., there were 57 per cent who experienced cramping; 19 per cent dizziness; 14 per cent nausea (one case associated with emesis); 14 per cent flushing; and small numbers who complained of cardio- or laryngospasm, headache, desire to defecate or to urinate, tingling of breasts, tinnitus, and palpitation. Very few of the symptoms can be attributed to the psychic effect of an intravenous injection. Also, there were 58 per cent who developed a transient rise in blood pressure after intravenous ergonovine. Thus, one must conclude that a therapeutic dosage of ergonovine given intravenously can produce definite, distressing symptoms which are transient and variable.

The presence of isospin coupling in the incident channel is observed as anomalous behavior in $^{98}\mathrm{Mo}$+$p$ excitation functions for proton, deuteron, and triton outgoing channels. Similarly shaped anomalies are simultaneously observed in several channels at threshold energies for the ($p, n$) reaction to the ground-state analog and to excited-state analogs of $^{98}\mathrm{Mo}$. The latter imply coupling through a deformation of the isospin-dependent potential.

This report describes the results of an experiment to measure the natural gamma radiation emitted from the earth's surface with the aid of radiation detectors mounted in an aircraft. For comparison, two detector systems were used: an array of intrinsic germanium detectors with a total active volume of 0.4 liter and a single NaI(Tl) scintillation detector 30.5 cm diam X 30.5 cm long. Data were recorded on flights at altitudes of 60, 120, 240, 300 and 5100 meters and with average airspeed of 200 knots. A discussion is presented on the application of germanium detectors to the atmospheric radon problem; in particular, on the use of the photons with energy 295, 352 and 609 keV to determine the respective contributions from the air and the surface.

This report researches a concept for a high efficiency detector of fast neutrons (several MeV), using solid state charged particle detectors overlaid with thick disks (about mm) of 238U. Experiments show a significant count rate in our mock-up when exposed to a fast neutron flux, but it appears insensitive to the slow/thermal neutron flux. Our preliminary results indicate a system with an efficiency on the order of at least 5% could be developed. Keywords: Fast neutron; Fission; High efficiency; Neutron detectors.

ABSTRACT The Glomar Beaufort Sea I was successfully mobilized to its first drilling location, the Exxon Antares prospect in the Alaskan Beaufort Sea, only 13-1/2 months after go-ahead. The paper reviews the completion of construction, describes the site surveys and its characterization, and details mobilization operations from Japan to Alaska. INTRODUCTION The Glomar Beaufort Sea I, a Concrete Island Drilling System (CIDS), is a United States Coast Guard certified Mobile Offshore Drilling Unit (MODU) and is classed by the American Bureau of Shipping as a Maltese Cross A-I Caisson Drilling Unit. Its structure is comprised of three basic stacked components:A compartmented A537 steel Mud Base 312 ft in length, 295 ft in breadth and 25 ft deep with raked sides.A central core prestressed and post-tensioned concrete BRICK, octagonal in shape, 234 ft across the flats, 44 ft in height, straight sided.An EH-36 (modified to -60"F) steel deck unit,290.5 ft in length, 274 ft in breadth, and 26 ft deep with raked sides built as two independent deck barges. The Glomar Beaufort Sea I (CIDS) was installed on its initial Alaskan Beaufort Sea drill site, the Exxon Antares' prospect, only 13.5 months after a letter of intent was signed with the Nippon Kokan (NKK) shipyard in Japan and 10 months after the first concrete was poured. At the peak of activity, 4 shipyards and 2 offsite facilities utilizing over 1600 workers were engaged in fabricating the principal sub-assemblies: mud base, brick, port and starboard deck barges, drill rig, and quarters. Numerous papers and articles have detailed the design (References 1 through 15). This paper summarizes the completion of construction and its mobilization to the drill site. CONSTRUCTION COMPLETION Mud Base Construction Construction of the Mud Base began at NKK's Tsurumi Works on September 28, 1983 and continued until March 13, 1984. The Mud Base was launched by skidding it onto a submersible barge. This created an interesting multiple degree of freedom problem involving variable and offset loads and inclination of the barge coupled with tidal effects that the shipbuilder resolved with a computer controlled barge ballast system. The Mud Base was then launched from the barge and towed 250 miles from the Tsurumi works to the Tsu works to await assembly with the BRICK. After arrival at Tsu, a 3 inch thick asphalt rubber compound was applied hot over the entire top of the Mud Base within the shear curb using conventional road building equipment to evenly distribute the load from the BRICK into the Mud Base structure. The asphalt rubber compound was developed and tested under contract by B.A. Va11erga, Inc. and consisted of 15% asphalt paving grade binder, which contained 20% ground vulcanized rubber, and 85% aggregate, made up of 70% clean dry river sand and 30% Meso1ite.