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In this brief review, we summarize the current state of knowledge of solar energetic particles. This includes energetic particles contained within the site of solar flares that are responsible for X-ray, γ-ray and neutron emission and particles accelerated at high coronal altitudes and in interplanetary space by travelling disturbances such as coronal mass ejections. Special emphasis is placed on those particles directly or indirectly associated with neutron monitor signals.

Long-duration solar γ-ray flares are those in which high-energy photon emission is present well beyond the impulsive phase, indicating the presence of either stored or continuously accelerated ions. We review both the observations and the current theories or models that can explain this unusual phenomenon. The present situation favors either acceleration of protons and ions for long periods of time by second order Fermi acceleration in large coronal loops or acceleration in large-scale, CME-associated reconnection sheets. Observations in the upcoming solar maximum may resolve this problem.

The Coastal Wetlands Management Project (CWMP), funded by the Global Environment Facility and implemented by the Ghana Wildlife Department, seeks to preserve the ecological integrity of coastal lagoons that serve as important sites for migratory waterbirds. This report describes the geomorphology, hydrology, soils, water chemistry, and vegetation of the Muni-Pomadze Ramsar site. Muni lagoon is a saline, shallow water lagoon separated from the sea by a sand bar which may be breached occasionally. The bulk of the rainfall in the catchment evaporates or flows as surface runoff into three streams that empty into Muni lagoon. Open water in the lagoon varies seasonally from 100 ha in the dry season to over 1000 ha in the wet season. The natural flora of the site can be divided into four main types; flood plain (including mangrove and wetland vegetation), dune vegetation, riverine vegetation, and terrestrial vegetation on elevated ground. The latter consists of a combination of grasslands, thickets, and Eucalyptus plantations. Fifty-three percent of the site is classified as natural vegetation. An additional 32.5% is agricultural land and 12.6% is residential area for the 11 communities within the site. The main source of employment are farming or fishing. The area surrounding Muni lagoon is used extensively for bushmeat hunting and as the tribal hunting grounds of the Efutu people. Apart from the global importance of the Muni-Pomadze site for biodiversity, management of the site is further justified by its considerable potential for development as an income-generating and educational nature reserve with an eco-cultural theme, managed by the local communities in partnership with the governmental and non-governmental conservation agencies.

A survey of the terrestrial mammal fauna of Muni-Pomadze Ramsar site along the Ghana coastline recorded 13 species, with 9 additional species reported by local villagers. Small mammal communities are most diverse in the grassland-thicket habitats surrounding the lagoons. Less diverse communities were present in and around managed Ecalyptus plantations or near villages. Duikers, antelope, bushbuck (Tragelaphus scriptus), and cane rats (Thryonomys swinderianus) are hunted (or trapped) for bushmeat. Bushbuck, in particular, play an important role in certain cultural ceremonies at Muni-Pomadze. Conservation efforts at these localities should focus on the management of bushmeat species and the establishment of a long-term monitoring program using small mammal communities as bioindicators of the health of the terrestrial habitats bordering Muni Lagoon.

We have compared the intensity-time profiles of the pion-related γ-ray emission (∼70 MeV) and the high-energy interplanetary solar protons in the 1990 May 24 and 1982 June 3 solar flare events. The results of the analysis of these events clearly indicate that the bulk of the interacting and interplanetary high-energy solar protons were not accelerated at the same time and in the same location at or near the Sun. Taking into account the different propagation times, the peak γ-ray emission in the 1990 May 24 event occurred ∼20 min. before the maximum intensity of the high-energy interplanetary protons. In the 1982 June 3 flare event the maximum γ-ray emission occurred at least 15 min before the intensity maximum of the interplanetary protons. Comparisons of the long-duration pion-related γ-ray emissions with the >355 MeV solar proton increases near the Earth in the 1991 June 11 and 15 solar flare events are inconclusive because the propagation of the interplanetary solar protons was diffusive.

COMPTEL observations of the Orion/Monoceros region have shown distinct evidence for excessive 3-7 MeV emission that was attributed to nuclear de-excitation lines from accelerated 12C and 16O nuclei. Unfortunately, we must conclude now that this appears to be a spurious result. This conclusion follows from a better understanding of the instrumental background, from a better exposure of the region, and from an improved analysis method. We show here how the impact of each of these gradually reduces the signal to a less than 3 σ result. The prime underlying cause seems to be 24Na activation in and around the upper COMPTEL detectors. Combining all available data, we now set a 2 σ flux upper limit on the 3-7 MeV emission of Orion of 3 × 10-5 γ cm-2 s-1, to be compared with the previously derived flux of ~10-4 γ cm-2 s-1.

We have been developing a Compton scatter polarimeter for measuring the linear polarization of hard X-rays (100-300 keV) from astrophysical sources. A laboratory prototype polarimeter has been used to successfully demonstrate the reliability of our Monte Carlo simulation code and to demonstrate our ability to generate a polarized photon source in the lab. Our design concept places a self-contained polarimeter module on the front-end of a a 5-inch position sensitive PMT (PSPMT). We are currently working on the fabrication of a science model based on this PSPMT concept. Although the emphasis of our development effort is towards measuring hard X-rays from solar flares, our design has the advantage that it is sensitive over a rather large field-of-view (>1 steradian), a feature that makes it especially attractive for /spl gamma/-ray burst studies.

Milagro will be the first water-Cerenkov detector specifically built to study extensive air showers. It is being built in an existing man-made pond located near Los Alamos, NM. Milagro will be the only air shower detector to have an energy threshold as low as a few hundred GeV and an angular resolution as good as 0.3°. Milagro will observe the entire overhead sky at all times. We describe here the Milagro detector, it capabilities and its physics goals.

In order to gain insight on a proposed CZT imaging device with orthogonal coplanar anodes currently under development, measurements have been made on an available commercial device with pixels and control electrodes. Charge signals induced on both the pixel and control electrodes by alphas incident at two positions on the cathode side are measured and compared with model predictions. Signals produced by c-rays are also discussed. Measurements and simulations are found to be in reasonably good agreement. It is concluded that the proposed anode geometry might exhibit excellent energy resolution and good position resolution in two dimensions as well as some position information along the depth dimension. ( 1999 Elsevier Science B.V. All rights reserved.

We report on a prototype detector system designed to perform imaging and spectroscopy on 20–250 MeV neutrons. The detection techniques employed can be applied to measurements in a variety of disciplines including solar and atmospheric physics, radiation therapy and nuclear materials monitoring. The detector measures the energy and direction of neutrons by detecting double neutron–proton scatters and recording images of the ionization tracks of the recoil protons in a densely packed bundle of scintillating plastic fibers stacked in orthogonal layers. The scintillation tracks are detected and imaged by photomultipliers and image intensifier/CCD camera optics. By tracking the recoil protons from individual neutrons, the kinematics of the scatter are determined. This directional information results in a high signal-to-noise measurement. The self-triggering and track imaging features of a prototype for tracking in two dimensions are demonstrated in calibrations with 14–65 MeV neutrons, 20–67.5 MeV protons, and with cosmic-ray muons. Preliminary results of phantom imaging measurements using a proton beam are also presented. We discuss several applications for this detector technique and outline future development work.

Centaurus A (Cen A, NGC 5128) is the nearest active galaxy and, notably, the viewing angle with respect to the jet axis is very large (> 70°). A first contemporaneous OSSE, COMPTEL, and EGRET spectrum obtained in October 1991 covers an energy range from 50 keV up to 1 GeV. This γ-ray broad-band spectrum was taken when Cen A was in an intermediate emission state as defined by the BATSE X-ray light-curve. The first simultaneous multiwavelength spectrum from radio to γ-rays was measured in July 1995 when Cen A was in a low emission state (the prevailing state for the last 7 years). The different spatial and temporal resolution in the different frequency regimes produces problems in the construction and interpretation of the multiwavelength spectra. These are addressed in this paper. The detection of emission > 1 MeV makes the inclusion of such high-energy emission into models for the spectral energy distribution mandatory.

Vehicle ownership plays a key role in determining the number of trips made by a household and the modes that the household will use to make those trips. Predicting vehicle ownership is a challenge due to the complexity of relationships affecting the choice of vehicles for a particular household. The income of the household, the accessibility of activities by alternative modes, and the family makeup of a household all affect the choice of the number of vehicles. The Honolulu metropolitan statistical area, which encompasses the island of Oahu, is the primary study area. On Oahu, vehicle ownership varies widely, from the dense neighborhoods in Waikiki to the semirural areas on the fringe of the region. Consequently, the vehicle-ownership model will be a crucial component of the new travel forecasting models for the island. Using 1995 Oahu household interview survey data, a vehicle-ownership model that takes into account income, accessibility, and household family structure has been estimated and found to predict rather accurately the shares in each vehicle-ownership class by geography, household size, and number of workers. In addition, 1990 census data have been used to test a variation of the vehicle-ownership model on several other American cities such as Atlanta, Kansas City, San Francisco, and New York. The resulting models for these regions parallel the Honolulu vehicle-ownership model very closely in structure and statistical significance, thereby demonstrating the model structures’ transferability between regions.

We identify a novel histochemical fibre type that is correlated with a unique myosin heavy chain isoform in the pectoralis muscle of the two bats Artibeus lituratus and Carollia perspicillata (Phyllostomidae). Pectoralis muscles sampled from four other species (Phyllostomus hastatus, Platyrrhinus helleri, Glossophaga soricina, and Diaemus youngi) exhibited myosin heavy chain isoforms with electrophoretic properties identical with those of A. lituratus andC. perspicillata. The pectoralis muscles of A. lituratus and C. perspicillata consisted mainly of the newly described type IIe fibre. Diaemus youngi differed from the other species studied by having an FM5 native myosin isoform, a feature shared with Desmodus rotundus. We hypothesize that the two-fibre-type composition of the pectoralis muscle in the phyllostomid bats may be related to a "two-gear" locomotor strategy and represents a synapomorphy. The distribution of fibre types and myosin isoforms correlated with family-level phylogenetic affinity rather than with functional characteristics. One of the fibre types was identical with type IIa of terrestrial mammals and a correlated IIa isoform pattern upon electrophoretic analysis. The IIa fibres had high oxidative and glycolytic potential. The second fibre type, which we call type IIe, had a histochemical and immunocytochemical pattern inconsistent with interpretation as a type IIb muscle fibre. Electrophoretic analysis confirmed that isoforms correlated with IIe fibres migrated at different rates from type I, IIa, IIb, and IIx isoforms. The IIe fibres had a fast oxidative metabolic pattern and were at least twice as numerous as IIa fibres. Thus, a novel type IIe fibre is predominant in the pectoralis of six phyllostomid species that exhibit highly divergent body sizes and (or) flight styles.

We report on recent tests and computer simulations of a sub-millimeter pitch CdZnTe strip detector under study as a prototype imaging spectrometer. This paper presents new measurements and new analyses of previous measurements of the CdZnTe transport properties for this prototype and resolves previously reported quantitative discrepancies. Measurements of charge signals produced by /spl alpha/-particles are used to determine the transport properties. These are then used in the model to predict detection efficiencies and spectroscopic performance for /spl gamma/-rays that are compared with the data.

We present three gamma-ray-burst spectra for bright bursts over very wide energy ranges. These were created from BATSE, COMPTEL, and OSSE data. The three spectra are for GRB 910503 (from 20 keV to 300 MeV), GRB 910601 (from 28 keV to 10.5 MeV), and GRB 910814 (from 103 keV to 500 MeV). A composite spectrum of 19 bright bursts is presented from 41 keV to 1.9 MeV (with no weak lines visible) for use in calculating average redshift corrections in cosmological models. Expanding fireball models with shocked synchrotron emission are predicted to have low-energy spectral slope (νFν ∝ να) that asymptotically approaches α = 4/3 such that α should never exceed 4/3. This prediction is tested with more than 100 bright bursts with BATSE and Ginga data. Over 90% of the bursts have spectral slopes in agreement with this prediction. For only one burst (GRB 870303, which has reported cyclotron lines) can a strong case be made that the slope violates the model limit, and then only from 2-5 keV.

We describe the development of a new balloon-borne telescope known as MARGIE (Minute-of-Arc Resolution Gamma ray Imaging Experiment). It is a coded aperture telescope designed to image photons (in various configurations) over the 20–600 keV range with an angular resolution approaching 1′. MARGIE will use one (or both) of two different detection plane technologies. One such technology involves the use of Cadmium Zinc Telluride (CZT) strip detectors, for which we have successfully demonstrated a spatial resolution of

The neuromotor conservatism hypothesis predicts that neuromotor patterns in homologous tetrapod muscles are conserved evolutionarily despite the musculoskeletal modifications of vertebrate limbs. A complete description of the anatomical organization of the neurons innervating homologous limb muscles is a prerequisite to any test of the neuromotor conservatism hypothesis. This study uses the retrograde neuronal tracer WGA-HRP to selectively label the motor neuron pools of seven homologous forelimb muscles in mice (Mus musculus) and iguanas (Iguana iguana): Mm. pectoralis, spinodeltoideus, biceps brachii, lateral and long heads of triceps brachii, and the supraspinatus and infraspinatus (in mice) or their reptilian homolog, the supracoracoideus (in iguanas). In vertebrates, motoneurons are arranged in longitudinal columns of cells in the ventral horn of the spinal cord. Mouse motor pools average 1,952 μm in length, except the pectoralis pool which averaged 2,949 μm in length. Iguana pools average 3,196 μm in length. The number of neurons per pool ranged from 70–199 in mice and from 58–114 neurons in iguanas. In both iguanas and mice the motor pools for the spinodeltoids, biceps, and the supracoracoideus (or its mammalian homologs) lie anterior to the pectoralis and triceps motor pools. In the transverse plane, the pectoralis pool lies medial to those of the triceps. The pools of the biceps and spinodeltoids are located dorsal and lateral to those of the pectoralis and supracoracoideus (or its homologs in mammals). The resulting motor pool maps support the hypothesis that the anatomical organization of motoneurons in ancestral reptiles has been retained in these two tetrapod descendents.

We present results from the spectral analysis of 29 gamma-ray bursts measured by the COMPTEL Telescope instrument (0.75–30 MeV) during the period from April 1991 through May 1995. The time-averaged spectra of these events are consistent with a simple power law model with spectral index in the range 1.5–3.5, whereas simple thermal models are statistically inconsistent with the burst sample. We find good agreement between burst spectra measured simultaneously by BATSE, COMPTEL and EGRET, which typically show a spectral transition or “break” in the BATSE energy range around a few hundred keV followed by simple power law emission extending to hundreds of MeV. Observations of rapid intensity variations up to a few MeV in the stronger bursts are used to investigate the importance of photon-photon opacity and to place limits on the source distance and bulk Lorentz factor.

On four occasions, twice in 1991 (near solar maximum) and twice in 1994 (near solar minimum), one COMPTEL D1 detector module was used as an omnidirectional detector to measure the high-energy (> 12.8 MeV) neutron flux near an altitude of 450 km. The D1 modules are cylindrical, with radius 13.8 cm and depth 8 cm, and are filled with liquid scintillator (NE213A). The combined flux measurements can be fit reasonably well by a product of the Mt. Washington neutron monitor rate, a linear function in the spacecraft geocenter zenith angle, and an exponential function of the vertical geomagnetic cutoff rigidity in which the coefficient of the rigidity is a linear function of the neutron monitor rate. When pointed at the nadir, the flux is consistent with that expected from the atmospheric neutron albedo alone. When pointed at the zenith the flux is reduced by a factor of about 0.54. Thus the production of secondary neutrons in the massive (16000 kg) Compton Gamma-Ray Observatory spacecraft is negligible. Rather, the mass of the spacecraft provides shielding from the earth albedo.

The COMPTEL imaging telescope has measured γ-ray lines originating from decay of the radioactive isotopes 26Al and 44Ti: Imaging of the full sky in the 1.809 MeV line has presented a glow of nucleosynthesis from the plane of the Galaxy, yet with distinct irregularities on top of the expected emission from average nucleosynthesis. The measured sky profile can be understood as a composite of plausible sources. Alternatively, however, it may be interpreted as a mapping of regions of prominent nucleosynthetic activity from very massive stars. Current results favour massive stars as candidate sources, as supported from indications of spiral structure and from association of prominent emission with known massive-star rich regions. — The COMPTEL measurement of 44Ti gamma-rays from the Cas A supernova remnant presents the first detection of this isotope from supernova nucleosynthesis. Recent observations from CGRO Cycle 5 independently confirm the detection, consistent with previous results. With these data, further assessment of systematic effects is expected to yield a better absolute flux value from Cas A.

We report /spl gamma/-ray detection performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector. The detector is a prototype for /spl gamma/-ray astronomy measurements in the range of 20-200 keV. The prototype is a 1.5 mm thick, 64/spl times/64 orthogonal stripe CdZnTe detector of 0.375 mm pitch in both dimensions, with approximately one square inch of sensitive area. Using discrete laboratory electronics to process signals from an 8/spl times/8 strip region of the prototype we measured good spectroscopic uniformity and sub-pitch (/spl sim/0.2 mm) spatial resolution in both x and y dimensions. We present below measurements of the spatial uniformity, relative timing and pulse height of the anode and cathode signals, and the photon detection efficiency. We simulated the photon interactions and signal generation in the strip detector and the test electronics and we compare these results to the data. The data indicate that the cathode signal-as well as the anode signal-arises primarily from the conduction electrons rather than the holes. This presents a detection efficiency limitation which must be considered in the design of strip detector systems.

The solar cosmic-ray event on 1990 May 24 can be divided into three phases: a first impulsive production of γ-rays and greater than 200 MeV neutrons; a second slower phase during which there were high-energy protons at the Sun for ~20 minutes producing pions and high-energy neutrons; and a third phase when the protons observed by the IMP 8 and GOES spacecraft and by neutron monitors were injected into interplanetary space. This third phase started after the onset of the event but before the second phase had ceased. We found that high-energy neutron production occurred during the last 60 s of the impulsive phase and at least the first 19 minutes of the second phase. During the second phase the high energy-neutron and γ-ray emissions decayed more slowly than either the 2.2 MeV or 4-7 MeV γ-ray line emissions. A two-component neutron energy spectrum that changes between the first and second phases gives a reasonable fit to the count rate increase recorded by the Climax neutron monitor. From the fit we infer that the integrated neutron emissivity at the Sun was ~3.5 × 1030 sr-1 for E > 100 MeV. The maximum intensity of P > 1.5 GV solar protons near the Earth was 4.5 × 103 (m2 sr s)-1. The differential solar proton energy flux (dJ/dE) as a function of rigidity at the Sun can be described by an evolving power-law spectrum. We estimate that the number of escaping protons with E > 30 MeV in the third phase was 7%-14% of the number of protons required to produce the solar neutron increase at the Earth. Although it is attractive to assume that the interplanetary solar protons simply leaked out from the trapping region at the Sun, the data suggest that the interplanetary solar protons were not from the population of energetic particles that produced the neutron and γ-ray emissions but were freshly accelerated during the third phase of the solar flare.

We present new COMPTEL observations of the OrionyMonoceros region, confirming our previous report of excessive 3‐7 MeV emission which we tentatively attributed to nuclear deexcitation lines at 4.44 and 6.13 MeV fromaccelerated 12 Cand 16 Onuclei.Weshowfirstresultsfromacombinationofalldataobtainedduringthefirst five years of the mission, with emphasis on the extent of the emission region. The 3‐7 MeV radiation is observed at the 9 ssignificance level with aflux of (12.8H1.5) 310 25 gcm 22 s 21 , consistent with our previousfindings. Inaddition,wecanfirmlyconcludenowthatonesinglesourcecannotexplainthemeasuredintensitydistribution: we find that the emission extends over the complex (the Orion A and B and the Mon R2 clouds), but it may actually be due to a few localized source regions. Evidence (4.4 s) for emission from the Mon OB1yOB2 area isappearingaswell.Wepresentapreliminaryspectrum(notfullydeconvolved),whichindicatesthattheemission is widely spread over the 3‐7 MeV range, suggesting a dominantly broad-line origin from energetic C and O nuclei if indeed caused by nuclear lines. The spectrum shows features that might be due to splitting of the C and O lines, but further substantiation should come from forthcoming spectral analyses and new observations. Subject headings: acceleration of particles—cosmic rays—gamma rays: observations— nuclear reactions, nucleosynthesis, abundances

The present investigation provides further evidence of the conservation of motor nuclei in amniotes. The position of six forelimb and shoulder motor pools were mapped in two species of bat, Eptesicus fuscus and Myotis lucifugus. The intraspinal locations of motor pools were revealed by labeling with the retrograde neuronal tracer WGA-HRP injected into the bellies of six muscles: m. pectoralis, m. spinodeltoideus, mm. triceps brachii (long and lateral heads), m. infraspinatus, m. supraspinatus, and m. biceps brachii. The positions of the labeled motor pools were reconstructed from serial transverse and horizontal sections of the spinal cord. WGA-HRP-labeled cells were located midway between cervical spinal nerves four and five to midway between cervical spinal nerve eight and the first thoracic spinal nerve. Individual motor pools formed fusiform clusters of cells with little intermingling of neurons between adjacent motor pools. The pectoralis motor pool contained significantly more motoneurons than all other motor pools for M. lucifugus. The pectoralis pool in E. fuscus contained more motoneurons than the biceps, supraspinatus, and infraspinatus, but not the spinodeltoid or the triceps brachii. The biceps, spinodeltoid, infraspinatus and supraspinatus pools were located rostrally; the pectoralis and triceps pools caudally. The pectoralis pool was the most medial and the spinodeltoid pool was the most lateral. These data suggest that the locations of shoulder and forelimb motor pools are ontogenetically and phylogenetically conserved across tetrapods and independent of the function of the muscles in adults.

Since its launch in April of 1991, the COMPTEL experiment on the Compton Gamma-Ray Observatory has surveyed the entire sky in the energy range of 0.75–30.0 MeV. Here we survey the latest results obtained from the COMPTEL data with respect to galactic black hole candidates. The most prominent such object, Cygnus X-1, is also one of the brightest sources observed by COMPTEL . In addition, we report on the progress of a full survey of the sky, searching for evidence of MeV emission from other black hole candidates.

We have examined six solar neutron events measured by satellite instruments and/or neutron monitors (NM) to understand the relationship between the intensity–time profiles of the γ-ray lines, the pion-related γ-rays, and the neutron production. In all six events the solar neutron production was clearly time-extended. We find that neutron emission as detected by NMs most closely follows the emission of pion-related γ-rays, whereas lower energy neutron production may follow that of nuclear γ-ray line emissions. Although this distinction is not unexpected, it is safe to say that the 2.223 MeV γ-ray line from neutron capture on hydrogen is a poor measure of the neutron production at energies >200 MeV. During the three events on 1982, June 3, 1990, May 24 and 1991, June 4 solar neutrons with energies greater than 200 MeV were recorded by NMs. The NM increases on 1982, June 3 and 1990, May 24 can be modeled using the time profile of the pion-related γ-rays. For the 1991, June 4 event the NM signal was small but lasted for ∼60 min and the high-energy γ-ray data available to us are insufficient to conclude unambiguously that the high-energy neutron production followed the pion-related γ-rays. In the other three events on 1991, June 9, 11, and 15 solar neutrons with energies 10–100 MeV were observed by the COMPTEL γ-ray instrument on the Compton Gamma Ray Observatory. The duration of the low-energy neutron production on 1991, June 9 corresponded clearly to the high-energy and not to the low-energy γ-ray emission.

The editors and authors recommend the code of behaviour that follows and completes this handbook.

To examine the theme from a European perspective and from an American perspective To examine the world before and after 9/11 To describe the failed state and its significance To introduce the concepts of globalisation and disintegration To suggest means of staying safe in these new environments

The authors of this chapter include specialists, many of whom have extensive deployment experience. The target group of this chapter, however, is not their fellow specialists, but the “junior” doctors, trying to help them find their way in the difficulties posed by an “adverse” environment. That junior doctor will be confronted by all imaginable ailments and injuries and should be a true generalist. As we’re all aware, even in medical school nowadays, there’s a tendency to make students choose the direction of their future work at an ever earlier stage, the opposite of what’s needed for a generalist.

We describe the science motivation and development of a pair production telescope for medium-energy gamma-ray polarimetry. Our instrument concept, the Advanced Energetic Pair Telescope (AdEPT), takes advantage of the Three-Dimensional Track Imager, a low-density gaseous time projection chamber, to achieve angular resolution within a factor of two of the pair production kinematics limit (~0.6 deg at 70 MeV), continuum sensitivity comparable with the Fermi-LAT front detector (, Version to be published in Astroparticle Physics, 32 pages, 11 figures

The Gamma RAy Polarimeter Experiment (GRAPE) was first flown on a 26-hour balloon flight in the fall of 2011. GRAPE consists of an array of Compton polarimeter modules (based on traditional scintillation technologies) designed to operate in the energy range from 50 keV up to 500 keV. The ultimate goal is to operate GRAPE in a wide FoV configuration for the study of gamma-ray bursts. For the first (demonstration) balloon flight, GRAPE was configured in a collimated mode to facilitate observations of known point sources. The Crab nebula/pulsar, the active Sun, and Cygnus X-1 were the primary targets for the first flight. Although the Crab was detected, the polarization sensitivity was worse than expected. This paper will review the plans for the next GRAPE balloon flight, which is scheduled to take place in the fall of 2014 from Ft. Sumner, NM. These plans involve several modifications designed to improve the polarization sensitivity, including an expansion of the array of polarimeter modules from 16 to 24 and improvements to the instrument shielding. Sensitivity estimates of the resulting instrument, based on GEANT4 simulations, will be presented.

Space-based gamma-ray detectors for high-energy astronomy face strict constraints of mass, volume, and power, and must endure harsh operating environments. Scintillator materials have a long history of successful operation under these conditions, and new materials offer greatly improved performance in terms of efficiency, time response, and energy resolution. The use of scintillators in space remains constrained, however, by the mass, volume, and fragility of the associated light readout device, typically a vacuum photomultiplier tube (PMT). Recently developed silicon photomultipliers (SiPMs) offer gains and efficiencies similar to those of PMTs, but with greatly reduced mass and volume, high ruggedness, and no high-voltage requirements. We have therefore been investigating the use of SiPM readouts for scintillator gamma-ray detectors, with an emphasis on their suitability for space- and balloonbased instruments for high-energy astronomy. We present our most recent results, including spectroscopy measurements for lanthanum bromide scintillators with SiPM readouts, and pulse-shape discrimination using organic scintillators with SiPM readouts. We also describe potential applications of SiPM readouts to specific highenergy astronomy instrument concepts.

We present the test results of a neutron/gamma-ray imaging spectrometer for the identification and location of radioactive and special nuclear materials. Radioactive materials that could be fashioned into a radiation dispersal device typically emit gamma rays, while fissile materials such as uranium and plutonium emit both neutrons and gamma rays via spontaneous or induced fission. The simultaneous detection of neutrons and gamma rays is a clear indication of the presence of fissile material. The instrument works as a double-scatter telescope, requiring a neutron or gamma ray to undergo an interaction in two detectors to be considered a valid event. While this requirement reduces the detector efficiency, it yields information about the direction and energy of the incident particle, which is then used to reconstruct an image of the emitting source. Because of this imaging capability background events can be rejected, decreasing the number of events required for high confidence detection and thereby greatly improving its sensitivity. The instrument is optimized for the detection of neutrons with energies from 1-20 MeV and gamma rays from 0.4 to 10 MeV. Images and energy spectra for neutron and gamma rays are reported for several sources including depleted uranium and plutonium. In addition, the effect of neutron source shielding is investigated.

The High Altitude Water Cherenkov (HAWC) observatory is an array of large water Cherenkov detectors sensitive to gamma rays and hadronic cosmic rays in the energy band between 100 GeV and 100 TeV. The observatory will be used to measure high-energy protons and cosmic rays via detection of the energetic secondary particles reaching the ground when one of these particles interacts in the atmosphere above the detector. HAWC is under construction at a site 4100 meters above sea level on the northern slope of the volcano Sierra Negra, which is located in central Mexico at 19 ° N latitude. It is scheduled for completion in 2014. In this paper we estimate the sensitivity of the HAWC instrument to point-like and extended sources of gamma rays. The source fluxes are modeled using both unbroken power laws and power laws with exponential cutoffs. HAWC, in one year, is sensitive to point sources with integral power-law spectra as low as 5 × 10 - 13 cm - 2 sec - 1 above 2 TeV (approximately 50 mCrab) over 5 sr of the sky. This is a conservative estimate based on simple event parameters and is expected to improve as the data analysis techniques are refined. We discuss known TeV sources and the scientific contributions that HAWC can make to our understanding of particle acceleration in these sources.

We report performance measurements of a sub-millimeter resolution CdZnTe strip detector developed as a prototype for astronomical instruments operating with good efficiency in the 30-300 keV photon energy range. The prototype is a 1.4 mm thick, 64/spl times/64 contact stripe CdZnTe array of 0.375 mm pitch in both dimensions. Pulse height spectra were recorded in orthogonal-stripe coincidence mode which demonstrate room-temperature energy resolution 5:1. Good response is also demonstrated at higher energies using a coplanar grid readout configuration. Spatial resolution capabilities finer than the stripe pitch are demonstrated. We present the image of a /sup 133/Ba source viewed through a collimator slit produced by a 4/spl times/4 stripe detector segment. Charge signals from electron and hole collecting contacts are also discussed.

In its first three years of operation, the COMPTEL instrument on theCompton Gamma-Ray Observatory has measured the locations (mean accuracy ∼1°) and spectra (0.75-30 MeV) of 18 gamma-ray bursts and continues to observe new events at a rate of ∼1/month. With good angular resolution and sensitivity at MeV energies, the growing COMPTEL burst catalog is an important new piece of evidence in the on-going GRB mystery. The COMPTEL burst locations are consistent with an isotropic distribution of sources, yet the spatial coincidence of two of the bursts indicates the possibility of repetition. The COMPTEL burst spectra are in most cases consistent with a single power law model with spectral index in the range 2–3. However, two bursts show evidence of a spectral break in the MeV range. Measurement of rapid variability at MeV energies in the stronger bursts provides evidence that either the sources are nearby (within the Galaxy) or the gamma-ray emission is relativistically beamed. We present an overview of analysis results obtained from the COMPTEL burst catalog concentrating on the search for burst repetition and the implications of highly variable MeV emission.

The BATSE/COMPTEL/NMSU Rapid Response Network (RRN) was formed to provide rapid follow-up ofγ-ray bursts imaged by the COMPTEL instrument on the Compton Gamma-Ray Observatory. The RRN consists of ≈ 22 professional observatories located around the world spanning both northern and southern hemispheres. Also included in the RRN is the Airforce GEODSS network. The goal of the RRN is to perform optical and radio observations of COMPTEL error boxes as soon after the burst as possible. We present results from the first two years of operation of this network.

CATSAT is a small, fast and cheap space mission currently funded for Phase A studies under the Student Explorer Demonstration Initiative (STEDI) by University Space Research Association. Its prime scientific objective is to determine burst distances by measuring their spectra at energies from 200 keV observations. The Hard X-Ray spectrometer consists of CaF2(Eu)-PMT detectors which are optimized in the cyclotron absorption energy band. The X-ray Albedo Polarimeter consists of nine collimated NaI-PMT detectors observing the earth reflected emission. Results from the XAP will be used to determine the burst direction and to place constraints on X-ray polarization. CATSAT was designed at three universities to be built with student help in two years for a cost of $3.5M.

Multiscale edge detection (MSED), using wavelet transform extrema, provides a robust method to compress the information in a transient signal. We apply this to gamma-ray burst (GRB) time series. Multiscale edge detection can be used to quantify the variability, identify structures (e.g. FREDs), and suppress noise. We present preliminary results of MSED applied to BATSE 64ms discsc data.

COMPTEL on board CGRO has observed a very strong (S[> 0.3 MeV] = 2.03 × 10−4 erg cm−2), complex, and long lasting (162 s) gamma-ray burst on February 17, 1994 (GRB 940217). Temporal fluctuations occur on timescales as short as 100 ms. Hard-to-soft spectral evolution has been observed during the burst emission and also within individual peaks. The photon spectra obtained within the 6 peaks can be modelled by single power law spectra and by broken power laws with break energies at around 1 MeV. The best-fit power law slopes vary between 1.1 and 3.5 throughout the event. The burst is located at [α 2000,δ 2000] = [29.5°, 3.8°] with a 3σ error radius of 0.9°. COMPTEL does not detect any significant “post-burst” emission (as reported by EGRET) at low energies (< 30 MeV), and our upper limits are marginally consistent with the EGRET detections. Using high energy spectral and temporal information, distance limits to GRB 940217 have been derived.

We present a multifractal analysis of GRB time series used to quantify the variability of the light curve. We discuss the advantages and disadvantages of multifractal analysis, including sensitivity to noise, and burst intensity, and present results for a few sample bursts.

Scintillators have long been used for probing the high energy universe. The reliability and low cost of scintillator-PMT detectors have made them the de facto standard for experiments on high altitude balloons and in orbiting satellites. New scintillators and new readout technologies offer important opportunities for more capable experiments. Recent scintillator developments include faster signals, increased light output, improved energy resolution, and better handling characteristics. Although PMTs remain effective for scintillator readout, new technologies offer more compact, rugged devices with much lower operational voltages. The adoption of these technologies is not without its difficulties, especially for space applications, where the technology readiness level can be an important consideration. To illustrate these issues, we will discuss the use of scintillators in Compton imaging experiments. At energies from about 500 keV to 30 MeV, Compton telescopes are the most effective means of imaging the gamma ray sky. To date, the only Compton telescope that has flown in space was the COMPTEL instrument on NASA's Compton Gamma Ray Observatory (CGRO). CGRO, launched in 1991 and de-orbited in 2000, was based entirely on the use of technologies from the 1980's. We have been working on an improved Compton telescope design, called the Advanced Scintillator Compton Telescope (ASCOT). It is much like COMPTEL, but utilizes up-to-date scintillator and readout technologies.

The Compton Gamma Ray Observatory (CGRO) completed a full sky survey in November 1993 during which the number of known gamma-ray pulsars more than doubled. During this survey the Compton Telescope (COMPTEL) observed the classical isolated pulsars Crab and Vela and detected PSR 1509-58. Attempts to detect the newly discovered pulsars, Geminga, PSR 1706-44 and PSR 1055-52, in the COMPTEL energy range provide only upper limits. The results of these analyses are presented together with the outcome of a search for further candidate radio pulsars whose ephemerides are given in the Princeton Pulsar Catalogue.

The sky region containing the active radio-galaxy Centaurus A has repeatedly been observed with the (COMPTEL) instrument onboard the Compton Gamma Ray Observatory (CGRO). The nine observation periods during the CGRO phases I and II in which Cen A was in the field of view of COMPTEL are spread over 18 months in the years 1991 to 1993. The energy range 0.75 to 30 MeV is covered. Clear evidence for a source with emission up to several MeV is seen from a region coinciding with the position of Cen A. The spectra change significantly over approximately 6 months between the two observation phases. A possible source confusion with the nearby gamma-ray source MS1312.1-4221 is discussed.

Neoplasms of the infrapatellar fat pad (IFP) although rare are a potential source of anterior knee pain and swelling. Masses comprised of cartilage and/or osseous tissues within the IFP have been reported with marked inconsistency. Diagnosis is based upon radiographic, surgical, and histologic characteristics. As a result, multiple terms and variable nomenclature have been used to describe these masses. We present a case of a benign cartilage neoplasm of the IFP that was successfully treated with surgical excision and a review of case reports and series of similar masses to aid in the diagnosis and treatment of intrinsic osseous and chondral neoplasms of the IFP.