Energy Technology Data Exchange (ETDEWEB)

Massive particle candidates for dark matter provide a potentially observable signature by virtue of their annihilations in the galactic halo at a known but model-dependent rate. Possible signatures are described, including cosmic ray antiproton and gamma-ray production. (orig.).

Energy Technology Data Exchange (ETDEWEB)

We construct the time-dependent radiation model for the pulsar wind nebulae (PWNe), assuming that leptons are accelerated in resonant scattering with heavy nuclei, which are injected into the nebula by the pulsar. The equilibrium spectra of these particles inside the nebula are calculated taking into account their radiation and adiabatic energy losses. The spectra of {gamma}-rays produced by these particles are compared with the observations of the PWNe emitting TeV {gamma}-rays and predictions are made for the expected {gamma}-ray fluxes from other PWNe. Expected neutrino fluxes and neutrino event rates in a 1 km{sup 2} neutrino detector from these nebulae are also calculated. It is concluded that only the Crab Nebula can produce a detectable neutrino event rate in the 1 km{sup 2} neutrino detector. Other PWNe can emit TeV {gamma}-rays on the level of a few percent of that ...

Science.gov (United States)

This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors investigated the evolution and radiation characteristics of individual neutron stars and stellar systems. The work concentrated on phenomena where new techniques and observations are dramatically enlarging the understanding of stellar phenomena. Part of this project was a study of x-ray and gamma-ray emission from neutron stars and other compact objects. This effort included calculating the thermal x-ray emission from young neutron stars, deriving the radio and gamma-ray emission from active pulsars and modeling intense gamma-ray bursts in distant galaxies. They also measured periodic optical and infrared fluctuations from rotating neutron stars and search for high-energy TeV gamma ...

International Nuclear Information System (INIS)

A time coincidence long baseline (250 km) cosmic ray detection system has been developed to search for bursts of high energy #gamma#-rays (E_0>= 10"1"3 eV) of extra-terrestrial origin. The system design incorporates the possibility of simultaneous observation over a variety of time scales between 1 #mu#s and 10 s. (Auth.).

Energy Technology Data Exchange (ETDEWEB)

Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.

International Nuclear Information System (INIS)

The resonant scattering of bremsstrahlung #gamma#-rays by a SrCO_3 target has been studied for #gamma#-ray energies of 5-11 MeV. Six #gamma#-transitions of energies between 6-8 MeV, which indicate six resonant states in "8"8Sr, were observed. The relative intensities of the resonantly scattered #gamma#-rays at 125 and 150"0 were found to be compatible only with the assignment of spin 1 to the six states. Radiative widths of the resonant states were deduced. The possibility that these states are components of the giant M1 resonance in "8"8Sr is discussed. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The flux of cosmic ray antiprotons with kinetic energies between /approximately/1 and 15 GeV is /approximately/5 times greater than the flux predicted on the basis of the leaky-box model. This excess is attributed to secondary antineutron production in compact sources. Because the antineutrons are not confined by the magnetic field of the compact source, they leave the interaction site, decay in interstellar space and account for the apparent excess cosmic ray antiproton flux. The escape and decay of neutrons produced in association with the antineutrons is a source of cosmic ray protons. Observations of the angular variation of the intensity and spectral shape of 100 MeV ..gamma..-rays produced by neutron-decay protons in the reaction p + p ..-->.. ..pi../sup 0/ ..-->.. 2..gamma.. could reveal compact-source cosmic ray production ...

CERN Document Server

Dark Matter annihilation (DMA) may yield an excess of gamma rays and antimatter particles, like antiprotons and positrons, above the background from cosmic ray interactions. Several signatures, ranging from the positron excess, as observed by HEAT, AMS-01 and PAMELA, the gamma ray excess, as observed by the EGRET spectrometer, the WMAP-haze, and constraints from antiprotons, as observed by CAPRICE, BESS and PAMELA, have been discussed in the literature. Unfortunately, the different signatures all lead to different WIMP masses, indicating that at least some of these interpretations are likely to be incorrect. Here we review them and discuss their relative merits and uncertainties. New x-ray data from ROSAT suggests non-negligible convection in our Galaxy, which leads to an order of magnitude ...

International Nuclear Information System (INIS)

Excited states in the T_z=(1/2) nucleus "8"5Mo have been observed for the first time with the reaction "5"8Ni("3"2S,#alpha#n#gamma#) at 105 MeV. #gamma#-ray transitions in this nucleus have been assigned unambiguously by combining the information from the GASP #gamma#-ray array, the ISIS silicon ball, and the n-Ring neutron detector. Two band structures have been observed in this nucleus; they continue the smooth evolution of the known bands from the lighter N=43 isotones and have been tentatively assigned spins and parity on this basis. After reaching a maximum of collectivity at "8"3Zr, the trend with increasing mass is reversed, showing a smaller collectivity at "8"5Mo. The rotational behavior of the observed bands is discussed on the basis of the projected shell model calculations.

Energy Technology Data Exchange (ETDEWEB)

Globular clusters are quite compact (size {proportional_to}10 pc) objects distributed spherically around the galaxy. They contain about 10{sup 5}-10{sup 6} mostly old stars. The number of millisecond pulsars in typical globular cluster is expected to be large (of the order of 100). We investigate the possible mechanism of production of high energy gamma-rays in those objects. Part of the wind energy of pulsars (energy conversion factor) is converted into relativistic leptons. Those leptons can upscatter in inverse Compton process low energy starlight and CMB photons and produce gamma-rays. MAGIC is an Imaging Atmospheric Cerenkov Telescopes located at Canary island of La Palma. We present results and discussion of the MAGIC observations of globular cluster M13.

CERN Document Server

A possible birefringence effect that arises in quantum gravity leads to a frequency-dependent rotation of the polarization angle of linearly polarized emission from distant sources. Here we use the UV/optical polarization data of the afterglows of GRB 020813 and GRB 021004 to constrain this effect. We find an upper limit on the Gambini & Pulin birefringence parameter $| \\eta | <2\\times 10^{-7}$. This limit is of 3 orders better than the previous limits from observations of AGNs and of the Crab pulsar. Much stronger limits may be obtained by the future observation of polarization of the prompt $\\gamma$-rays.

Science.gov (United States)

AGILE pointed observations performed from July 9, 2007 to October 30, 2009 are a recent, high quality gamma-ray data archive for monitoring studies of medium to high brightness gamma-ray sources in the 30 MeV -50 GeV energy range. We present a variability study of the 1AGL sources over the complete AGILE pointed Observation Blocks (OBs) dataset. The first AGILE Gamma-Ray Imaging Detector (GRID) catalog (Pittori et al. 2009) included a significance-limited (4 sigma) sample of 47 sources (1AGL), detected with a conservative analysis over a first-year non-uniform sky coverage dataset. In this analysis we used data of an improved full Field of View (FOV) event filter, on a much larger (about 27.5 months) observation dataset, analyzing each OB separatedly. This data processing resulted in an improved source list as compared to the 1AGL one. We present here some ...

International Nuclear Information System (INIS)

We study the spectral evolution of pulsar wind nebulae (PWNe) taking into account the energy injected when they are young. We model the evolution of the magnetic field inside a uniformly expanding PWN. Considering time-dependent injection from the pulsar and coolings by radiative and adiabatic losses, we solve the evolution of the particle distribution function. The model is calibrated by fitting the calculated spectrum to the observations of the Crab Nebula at an age of a thousand years. The spectral evolution of the Crab Nebula in our model shows that the flux ratio of TeV #gamma#-rays to X-rays increases with time, which implies that old PWNe are faint in X-rays, but not in TeV #gamma#-rays. The increase of this ratio is because the magnetic field decreases with time and is not because the X-ray emitting particles are cooled more rapidly than the TeV ...

CERN Document Server

The bright gamma-ray burst GRB050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UV afterglow decay light curves both exhibit a steeper slope ~0.15 days after the burst, indicative of a jet break. The timing of the jet break combined with the total gamma-ray energy of the burst constrains the opening angle of the jet to be 2.5 degrees. We derive an empirical `time-lag' redshift from the BAT data of z_hat = 0.69 +/- 0.02, in good agreement with the spectroscopic redshift of 0.61. Prior to the jet break, the X-ray data can be modelled by a simple power law with index alpha = -1.2. However after 300s the X-ray flux brightens by about 30% compared to the power-law fit. The optical/UV data have a more complex decay, with evidence of a rapidly falling reverse shock component that ...

International Nuclear Information System (INIS)

In Japan, cosmetics claiming hormesis effect are available through Internet. Although these cosmetics show the contents, they never mention the minor elements and radioactive sources. The existence of radioisotopes, however, was observed by measurements of the gamma-rays with a HPGe detector. In this study, in order to clarify the contents of trace elements, the hormesis cosmetics including radioactive sources were analyzed using INAA, PGAA and NAA with multiple gamma-ray detection (NAAMG). Nineteen elements were analyzed quantitatively in hormesis cosmetics by INAA, PGAA and NAAMG and 16 elements were detected qualitatively by SEM-EPMA. (author)

CERN Document Server

Gamma-ray burst (GRB) is one of the candidates of high-energy cosmic-ray acceleration sites. They may be also ultra-high-energy (above 3 EeV) cosmic-ray (UHECR) sources. In this paper, we discuss possibilities and implications of high-energy cosmic-ray acceleration in GRBs. (1) First, we show that not only protons but also heavier nuclei can be accelerated up to ultra-high energies in both usual high-luminosity (HL) and low-luminosity (LL) GRBs by using the Geant4. LL GRBs may also make a significant contribution to the observed UHECR flux if they form a distinct population, and we investigate cosmic-ray acceleration in LL GRBs in detail. (2) Second, we discuss implications of the GRB-UHECR hypothesis (and Hypernova-UHECR hypothesis) to cosmic-ray astronomy. HL GRBs and LL GRBs will lead to different source number densities as UHECR sources, ...

Energy Technology Data Exchange (ETDEWEB)

The young open cluster Berkeley 87 was predicted to be associated with the COS B {gamma}-ray source 2CG 075+00 on the basis of the experimental evidence of the presence of a shock front around the Wolf - Rayet star ST3 placed in the inner part of the cluster. The CGRO phase-1 data confirm this identification. Protons accelerated at the shock boundary can produce {pi} deg. via p-p interactions and then {gamma}-rays. With the measured flux F{sub {gamma}} (E > 100 MeV) {approx_equal} 9x10{sup -7} ph cm{sup -2} s{sup -1} and the power-law proton spectrum with spectral index {gamma} = 2, the cosmic-ray-energy-density in the inner part ({approx} 0.8 pc radius) of Berk 87 is about 100 times greater than that in the vicinity of the Earth. We have calculated {gamma}-ray spectra expected from the decay of {pi}{sup d}eg. produced in p-p interactions. The spectra ...

International Nuclear Information System (INIS)

Pregnant rats in 11d and 16d of their pregnancy were given one-off whole body exposure by "1"3"7Cs #gamma# rays to 0.2, 0.4, 0.9 and 2.0 Gy, respectively. Changes were observed in conditioned drinking response and cerebrum hippocampi cone cell number of the baby rats exposed to the #gamma# rays in different periods of their embryo development. As a result, that pregnant rats exposed to "1"3"7Cs #gamma# rays in different pregnant periods may induce significant decrease in cerebrum hippocampi cone cell number and achieving rate of conditioned drinking response of the babies. The dose-response relationship can be described by Y=a-b log_1_0D. The achieving rate of conditioned drinking response were significantly correlated to cerebrum hippocampi cone cell number in the babies, and the achieving rate of conditioned drinking response of the babies ...

CERN Document Server

Polarization measurements in the X-ray and gamma-ray energy range can provide crucial information on massive compact objects such as black holes and neutron stars. The Polarized Gamma-ray Observer (PoGO) is a new balloon-borne instrument designed to measure polarization from astrophysical objects in the 30-100 keV range, under development by an international collaboration with members from United States, Japan, Sweden and France. To examine PoGO's capability, a beam test of a simplified prototype detector array was conducted at the Argonne National Laboratory Advanced Photon Source. The detector array consisted of seven plastic scintillators, and was irradiated by polarized photon beams at 60, 73, and 83 keV. The data showed a clear polarization signal, with a measured modulation factor of $0.42 \\pm 0.01$. This was successfully reproduced at the 10% level by the computer simulation package Geant4 after ...

CERN Document Server

The association of at least some long gamma-ray bursts with type Ic supernova explosions has been established beyond reasonable doubt. Theoretically, the challenge is to explain the presence of a light hyper-relativistic flow propagating through a massive stellar core without losing those properties. We discuss the role of the jet-star interaction in shaping the properties of the outflow emerging on the surface of the star. We show that the nature of the inner engine is hidden from the observer for most of the evolution, well beyond the time of the jet breakout on the stellar surface. The discussion is based on analytical considerations as well as high resolution numerical simulations. Finally, the observational consequences of the scenario are addressed in light of the present capabilities.

Energy Technology Data Exchange (ETDEWEB)

The measurements of the L X-ray intensity ratio I(L{alpha})/I(L{beta}), I(L{alpha})/I(L{gamma}), I(L{alpha})/I(L{iota}), I(L{beta})/I(L{gamma}) and I(L{iota})/I(L{gamma}) for elements Dy, Ho, Yb, W, Hg, Tl and Pb were experimentally determined both by photon excitation, in which 59.5 keV {gamma}-rays from a filtered radioisotope {sup 241}Am was used, and by the radioactive decay of {sup 160}Tb, {sup 160}Er, {sup 173}Lu, {sup 182}Re, {sup 201}Tl, {sup 203}Pb and {sup 207}Bi. L X-rays emitted by samples were counted by a Si(Li) detector with resolution 160 eV at 5.9 keV. Obtained values were compared with the calculated theoretical values. Theoretical values of the I(L{alpha}/L{beta}), I(L{alpha}/L{gamma}), I(L{alpha}/L{iota}), I(L{beta}/L{gamma}) and I(L{iota}/L{gamma}) intensity ratios were ...

CERN Document Server

Primordial black holes are unique probes of cosmology, general relativity, quantum gravity and non standard particle physics. They can be considered as the ultimate particle accelerator in their last (explosive) moments since they are supposed to reach, very briefly, the Planck temperature. Upper limits on the primordial black hole number density of mass $M_{\\star} = 5 10^{14}$ g, the Hawking mass (born in the big-bang terminating their life presently), is determined comparing their predicted cumulative $\\gamma$-ray emission, galaxy-wise, to the one observed by the EGRET satellite, once corrected for non thermal $\\gamma$-ray background emission induced by cosmic ray protons and electrons interacting with light and matter in the Milky Way. A model with free gas emissivities is used to map the Galaxy in the 100 MeV photon range, where the peak of the primordial black hole emission is expected. The best ...

International Nuclear Information System (INIS)

Upon irradiation of aqueous ethylene glycol/water solutions of native chloroperoxidase (CPO) with "6"0Co-gamma rays at 77K one observes the one-electron reduction of the enzyme active site by radiolytically generated thermolyzed electrons. In the present study the first absorption spectrum of a low-spin ferrous form of CPO is reported which has peaks at 438, 532 and 563 nm, similar to those observed previously for cytochrome P-450. All previously described ferrous forms of CPO are high spin. In order to observe the final results of the CPO reaction with electrons, the spectral changes of native enzyme after room temperature-gamma-irradiation have also been investigated. Evidence of changes is also presented probably connected with disruption of the tertiary structure of enzyme, correlated with decrease of enzyme activity.

Science.gov (United States)

The research sponsored by this grant was conducted in two fields of high-energy astrophysics:

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

This patent describes a {gamma}-ray detector. It comprises: a dislocation-free single crystal having an input surface and a transmission surface at opposite ends thereof; an active shield surrounding the crystal and functioning as an anticoincidence counter; and {gamma}-ray detector means disposed adjacent the transmission surface of the crystal for receiving and detecting {gamma}-rays of a predetermined wavelength incident on the input surface of the crystal at a specific Bragg angle and transmitted through the crystal.

Science.gov (United States)

Thesis. Five-particle shell-model calculations, using a spin-dependent potential, were performed for the nucleus /sup 101/Tc. The effects of varying the single-particle energy differences and the strengths of the spin-dependent and pairing terms are discussed. The isobars /sup 101/Mo and /sup 101/Tc were chemically separated to enable the detailed study of their decay schemes. As a result, 184 gamma rays were observed in the decay of /sup 101/Mo, and 169 of them were assigned to 45 levels in /sup 101/Tc. In the decay of /sup 101/Tc, 27 gamma rays were observed, and 26 of them were assigned to 11 levels in /sup 101/Ru. In a study of the decays of /sup 142/Xe and /sup 142/Cs the TRI STAN on-line isotope separator was used to separate the 142 mass chain produced in /sup 235/U fission with /sup 142/2Xe as the emanating and accelerated ...

International Nuclear Information System (INIS)

The registration of secondary cosmic ray neutrons is a convenient tool for the investigation of primary cosmic ray variations and for meteorological effects as well. At present a large network of neutron monitors exists, aiming at studies of cosmic ray variations which are related to interplanetary conditions and geomagnetic activity. At the same time cosmic ray variations may be related to some atmospheric processes. In this connection, using the data from two neutron monitors (a standard and a lead free one), a gamma detector from Moscow station and lead free neutron monitor at BEO Moussala, we studied the correlations between rain flows and neutron flux. In this study we used daily averages on the basis of 10 min data for the neutron flux, corrected for barometric pressure and data from local meteo-stations. The preliminary analysis indicates a correlation between rain flows and ...

International Nuclear Information System (INIS)

The measurements of the K X-ray intensity ratio I(K#alpha# _2/K#alpha# _1), I(K#beta# _1/K#alpha# _1) and I(K#beta#/K#alpha#) for elements V, Mn, Zn, Tc, Ru, Cd, Xe, Ba, Cs, Hg and Rn were experimentally determined both by photon excitation, in which 59.5 keV #gamma#-rays from a "2"4"1Am and 123.6 keV #gamma#-rays from a "6"0Co were used, and following the radioactive decay of "5"1Cr, "5"5Fe, "6"7Ga, "9"9Tc, "1"1"1In, "1"3"1I, "1"3"3Ba, "1"3"3Xe, "1"3"7Cs, "2"0"1Tl and "2"2"6Ra. K X-rays emitted by samples were counted by a Si(Li) detector with resolution 160 eV at 5.9 keV. Obtained values were compared with the theoretical values. It was observed that present values agree with the previous theoretical and other experimental results.

CERN Document Server

Very high energy (VHE; >100 GeV) observations of a sample of selected active galactic nuclei (AGN) were performed between January 2005 and April 2007 with the High Energy Stereoscopic System (HESS), an array of imaging atmospheric-Cherenkov telescopes. Significant detections are reported elsewhere for many of these objects. Here, integral flux upper limits for twelve candidate very high energy (VHE; >100 GeV) gamma-ray emitters are presented. In addition, results from HESS observations of four known VHE-bright AGN are given although no significant signal is measured. For three of these AGN (1ES 1101-232, 1ES 1218+304, and Mkn 501) simultaneous data were taken with the Suzaku X-ray satellite.

Science.gov (United States)

Experimental measurements were made of the production cross sections and energy distributions of gamma rays emitted when the stable targets /sup 88/Sr, /sup 89/Y and /sup 90/Zr are exposed to protons in the energy range 3 to 8 MeV. The data are being analyzed using a recent version of the Uhl statistical model code. One conclusion is that while the gamma-ray strength functions employed reproduce the proton capture cross sections, they do not achieve the same degree of hardness observed in the measured spectra. To do so, their lower energy regions must be modified; such changes, however, do not affect the capture cross sections. 7 references.

International Nuclear Information System (INIS)

With the development of an array of highly-segmented germanium detectors, it now becomes possible to perform in-flight #gamma#-ray spectroscopy experiments on intermediate energy beams with unprecedented #gamma#-ray energy resolution. Presented in this report are examples of two techniques in which SeGA, the most highly-segmented operational germanium array for in-flight spectroscopy with fast beams, was used for the detection of #gamma# rays. SeGA used in conjunction with a high-resolution magnetic spectrograph (S800) to detect the reaction residues in coincidence represents a powerful combination for in-beam #gamma#-ray studies.

Science.gov (United States)

The NS together with a gamma ray sensor make up the Gamma- Ray and ... A simplified view of the interactions between incoming cosmic rays and the .... held in Huntsville, Alabama, at the U.S. Space and Rocket Center on January 2830. ...

CERN Document Server

Gamma-Ray Bursts (GRBs) are thought to originate at cosmological distances from the most powerful explosions in the Universe. If GRBs are not beamed then the distribution of their number as a function of gamma-ray flux implies that they occur once per (0.3-40) million years per bright galaxy and that they deposit >10^{53} ergs into their surrounding interstellar medium. The blast wave generated by a GRB explosion would be washed out by interstellar turbulence only after tens of millions of years when it finally slows down to a velocity of 10 km/s. This rather long lifetime implies that there could be up to several tens of active GRB remnants in each galaxy at any given time. For many years, radio observations have revealed the enigmatic presence of expanding neutral-hydrogen (HI) supershells of kpc radius in the Milky Way and in other nearby galaxies. The properties of some supershells cannot be easily explained in terms ...

International Nuclear Information System (INIS)

The decay of "1"0"1Mo to levels in "1"0"1Tc has been studied using the three-parameter (#gamma#-#gamma#-t) coincidence system of HpGe-HpGe detectors. According to the coincidence data, the decay scheme was modified. The positions of 221.80, 318.00, 377.90, 452.50, 515.42, 1011.05 and 1759.72 keV transitions have been arranged again, the transition positions of 104.70, 105.95 and 774.15 keV gamma-rays have been assigned for the first time, the positions of 169.00, 590.91, 980.52 and 1431.68 keV transitions have been reconfirmed, the 1508.01 keV gamma-ray was observed simultaneously for the first time and its transition position has been assigned. The #beta#-intensities and the values of log ft of most levels were calculated. (author)

Energy Technology Data Exchange (ETDEWEB)

Three possibilities to observe the Higgs-top interaction at future {gamma}{gamma}-colliders are discussed: (a) associated Higss production via the {gamma}{gamma}{yields}tanti tH reaction, (b) Higgs obliged radiative correction to the {gamma}{gamma}{yields}tanti t channel, (c) Higgs resonance production via {gamma}{gamma}{yields}H{yields}ZZ. The results obtained show windows of the Higss mass where the Yukawa interaction of the Higss with the top quark can be studied at {gamma}{gamma}-colliders. (orig.).

Energy Technology Data Exchange (ETDEWEB)

We discuss the search of excited leptons and quarks with spin 1/2 at {gamma}{gamma} and at {gamma}e colliders. We show that {gamma}{gamma} colliders have important advantages for the observation of excited leptons and quarks in comparison with ee, ep, and pp colliders discussed in previous papers. These collisions give a simple test for the chirality of the l{sup *}l{gamma} transition. The anomalous magnetic moment of excited leptons can be observed when its value is not too small. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Powders with nominal compositions (in atomic percent) Ti-48Al and Ti-48Al-2Nb-2Cr were prepared by the plasma rotating electrode process (PREP) and gas atomization (GA) techniques. As-solidified and heat-treated (1000degC per 3 h) powder samples were examined by metallography, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The microstructures of the powders were characterized as a function of atomization technique, alloy content, powder particle size (solidification rate) and thermal history. All of the as-solidified powders were comprised of disordered [alpha], and ordered [alpha][sub 2]-Ti[sub 3]Al and [gamma]-TiAl. For both alloys, a larger volume fraction of [alpha] and [alpha][sub 2] was observed in the PREP powders relative to GA powders of comparable size. Additionally, for both alloys and both atomization techniques, the volume fraction of [alpha][sub 2] was ...

Energy Technology Data Exchange (ETDEWEB)

The goal of this DOE-supported exhibition is to demystify Einstein`s formula E = mc{sup 2} by illustrating the interchangeability of matter (m) and energy (E), c{sup 2} being the exchange rate. The exhibition has two major parts, {open_quotes}matter into energy{close_quotes} and {open_quotes}energy into matter{close_quotes}, plus a video to connect them. {open_quotes}Matter into energy{close_quotes} has now been completed and has been placed on the museum floor. Positrons from a {sup 22}Na source are annihilated to produce gamma rays that are caught in NaI detectors. The viewer can alter the alignment of the detectors and observe the consequences for the rates of single and coincident counts. The viewer can also observe the effects of placing absorbers in front of the counters. Prototype explanatory graphics were placed around the exhibit and those will probably be changed after we have some experience ...

Energy Technology Data Exchange (ETDEWEB)

The structural variations of amorphous metals, such as Pd/sub 80/Si/sub 20/, with irradiation of helium ion, neutron, and gamma ray have been mainly pursued by the method of X-ray diffraction and thermal analysis. It should be noticed that the amorphous metals show a radiation resistance, that is, no remarkable structural changes under helium ion, neutron, and gamma ray irradiation.

International Nuclear Information System (INIS)

A brief description of the physical process of dose enhancement effects produced by X-ray radiation on materials is given, with emphasis on the influence on electronic devices. The damages caused by X-ray radiation dose enhancement is more serious than that of #gamma#-ray with higher energy.

International Nuclear Information System (INIS)

Samples from 314 broiler chickens at 2 months age were analyzed for blood serum level of lysozyme and 311 of them were analyzed also for activity of alternative path-way of complement activity (APCA). Chickens were hatched from eggs, irradiated immediately before incubation with different doses of gamma-rays using Rocus M device - group 1 - control (non irradiated), and groups 2, 3 and 4 - irradiated with doses of 0.15, 0.30 and 0.60 Gy, respectively. Lysozyme concentration was highest for the control group, and for the experimental ones it was lower (p<0.001) which is an indication of the strongly negative effect of gamma-rays on this indicator. For APCA the oppsite relationship was observed - increasing of its activity with increasing of irradiation dose (from p<0.05 to p<0.001) which gave reason to suggest that this phenomenon is due to the irradiation. 12 refs., 2 tabs. (author).

International Nuclear Information System (INIS)

An aerial radiological survey was performed from 11 to 20 March 1982 over a 260-square-kilometer area centered on the Grand Gulf Nuclear Station at Port Gibson, Mississippi (the station was not yet in operation at the time of the survey). All gamma ray data were collected by flying east-west lines spaced 152 meters apart at an altitude 91 meters above ground level. Processed data showed that all gamma rays detected within the survey area were those expected from naturally occurring terrestrial background emitters. Count rates obtained from the aerial platform were converted to exposure rates at 1 meter above the ground and are presented in the form of an isoradiation contour map. The observed exposure rates were between 5 and 13 microroentgens per hour (#mu#R/h), with most of the area ranging from 9 to 10 #mu#R/h. These values include an estimated cosmic ray ...

Energy Technology Data Exchange (ETDEWEB)

To study CdZnTe as a high energy resolution gamma ray detector with a novel new design, and to build a detector array from the new detector design

Energy Technology Data Exchange (ETDEWEB)

We summarize some initial results in our investigation of the nuclear physics issues of gamma-ray lasers. We describe what is known thus far from existing experimental data and illustrate how theoretical models may be employed for systematic searches of candidate nuclei.

CERN Document Server

If gamma-ray bursts originate in galaxies at cosmological distances, the host galaxy should be detected if a burst error box is searched deep enough; are the host galaxies present? We present and implement a statistical methodology which evaluates whether the observed galaxy detections in a burst's error box are consistent with the presence of the host galaxy, or whether all the detections can be attributed to unrelated background galaxies. This methodology requires the model-dependent distribution of host galaxy fluxes. While our methodology was derived for galaxies in burst error boxes, it can be applied to other candidate host objects (e.g., active galaxies) and to other types of error boxes. As examples, we apply this methodology to two published studies of burst error boxes. We find that the nine error boxes observed by Larson and McLean (1997) are too large to discriminate between the presence or absence of host ...

International Nuclear Information System (INIS)

Radiation damage and its recovery in the light emittance efficiency and the attenuation length of barium fluoride (BaF_2) scintillator have been investigated. The light yield and transmittance of small samples of BaF_2 scintillator were measured after #gamma#-irradiation from 0.5x10"4 to 1.1x10"5 Gy for deterioration, and after sunlight exposure for recovery. Suspension of deterioration was observed both in light yield and in attenuation length at an integrated dose of #gamma#-rays of about 10"4 Gy. Fairly good and quick recovery of the deteriorated BaF_2 scintillator was obtained by sunlight exposure. Using a Monte Carlo simulation method, the dependence of the light emittance efficiency on #gamma#-irradiation and sunlight exposure was studied. It has been found that the light emittance efficiency, as well as the attenuation length, is influenced by #gamma#-irradiation and sunlight ...

International Nuclear Information System (INIS)

Bulgarian (1973). Bulgaria Yankov, I. Sumrov, I. Stefanova, M. v.

Energy Technology Data Exchange (ETDEWEB)

In the early days of Moessbauer spectroscopy, it was demonstrated that coherent scattering of photons emitted by a Moessbauer source can be observed. In spite of the fact that scattering experiments could give information not accessible by the absorption method, they are not widely used. The reasons for this are, on the one hand, experimental difficulties, and on the other hand, the form of the samples, which should be large single crystals in most cases. In this work, we present a Moessbauer diffraction measurement on polycrystalline bcc iron where these problems have been overcome. We demonstrate that using the kinematical theory of gamma-ray diffraction, useful information on the relative orientation of the crystallographic axis to the hyperfine field directions can be subtracted. (orig.)

International Nuclear Information System (INIS)

An aerial radiological survey was conducted from August 10-16, 1993, over a 78-square-kilometer (30-square-mile) area of the Portsmouth Gaseous Diffusion Plant and surrounding area located near Portsmouth, Ohio. The survey was performed at a nominal altitude of 46 meters (150 feet) with a line spacing of 76 meters (250 feet). A contour map of the terrestrial gamma exposure rate extrapolated to 1 meter above ground level was prepared and overlaid on a set of United States Geological Survey topographic maps of the area and an aerial photograph of the plant. The terrestrial gamma exposure rates varied from about 7 to 14 microroentgens per hour at 1 meter above the ground. Protactinium-234m was observed at six sites within the boundaries of the plant. At a seventh site, only uranium-235 was observed. No other man-made, gamma ray-emitting radioactive material was ...

CERN Document Server

Based on BACODINE network notification the Whipple Observatory gamma-ray telescope has been used to search for the delayed TeV counterpart to BATSE-detected gamma-ray bursts. In the fast slew mode, any point in the sky can be reached within two minutes of the burst notification. The search strategy, necessary because of the uncertainty in burst position and limited FOV of the camera, is described.

Energy Technology Data Exchange (ETDEWEB)

The light curves produced by all-sky monitors, such as the Rossi X-ray Timing Explorer All-Sky Monitor and the Swift Burst Alert Telescope (BAT), generally have non-uniform error bars. In searching for periodic modulation in this type of data using power spectra it can be important to use appropriate weighting of data points to achieve the best sensitivity. It was recently demonstrated that for Swift BAT data a simple weighting scheme can actually sometimes reduce the sensitivity of the power spectrum depending on source brightness. Instead, a modified weighting scheme, based on the Cochran semi-weighted mean, gives improved results independent of source brightness. We investigate the benefits of weighting power spectra in period searches using simulated GLAST LAT observations of {gamma}-ray binaries.

Energy Technology Data Exchange (ETDEWEB)

Measurements of neutron and gamma-ray penetrations in an iron shield were performed up to a 60-cm depth in a tightly coupled source shield configuration with the fast-neutron reactor YAYOI as a source. Rates of neutron reactions and gamma-ray dose rates in the iron shield were obtained using activation foils and thermoluminescent dosimeters. Analyses of the experiments were made by using the DOT-III code with coupled neutron and gamma-ray cross sections from ENDF/B-IV and POPOP4 libraries. To obtain the source condition for the iron shield analyses, the calculated spectrum was adjusted to the measured reaction rates at the reactor shield boundary. The calculated neutron and gamma-ray distributions in the iron shield show fairly good agreement with the experiments. The effect of difference in Bondarenko-type self-shielding factors on the analyses of the iron shield is also shown.

Energy Technology Data Exchange (ETDEWEB)

A complete code based on the finite element method (FEM) is used to study the attenuation of gamma rays, of source energy 9 MeV, in simple homogeneous lead and water systems. The results are compared, in tables and graphs, with those produced by a Monte Carlo method of solution. In the comparison, particular attention is paid to the annihilation gamma rays generated by the pair production process, to energy deposition, and to the leakage spectra. A model, multilayer, slab shield, having a fission neutron source impinging on the left-hand face, is also solved by the FEM code, using data from a coupled neutron/gamma ray cross section library. The resulting neutron and gamma ray flux distributions, and the leakage spectra, are shown graphically. (author).

International Nuclear Information System (INIS)

Some aspects of metrological provision of X-ray radiometric analyzers for mineral raw composition and gamma-gamma-logging equipment are considered. Standard samples (SS) based on the phenol-formaldehyde resin with the introduced quantities calculated of element compositions in the form of oxides and salts are described. Principles of metrological provision developed are used when carrying out state acceptance tests of X-ray radiometric analyzer RAL-M-102 ''Ehkran'' and gamma-gamma-logging equipmnt RSK-102. Economic benefit from introduction of an SS set is #approx# 60-100 thousand roubles per year.

Energy Technology Data Exchange (ETDEWEB)

Recently, a drive laser for an S-band (2.86 GHz) rf photoinjector, designed to provide a pulse that has a flat temporal and spatial profile, has been built, commissioned, and put into service as part of the LLNL Compton-scattering monoenergetic {gamma}-ray source program. This laser is based on an all-fiber oscillator and front-end amplification system, and provides both the laser light to generate the electrons as well as the rf signal that is amplified to accelerate them. Now, a new 11.424 GHz photoinjector is being developed, which has required a revised design for the laser system. The higher frequency has placed more stringent requirements on the synchronization stability, delivered pulse length, and pulse rise times to maintain the desired emittance. Presented here are the overall design and measured performance of the current system and a discussion of what changes are being made to address observed shortcomings and more demanding ...

Energy Technology Data Exchange (ETDEWEB)

The effect of ionizing radiation (2, 5, and 10 KGy of gamma rays) on muscle ultrastructure of grass shrimps (Penaeus monodon Fabricius) tails at ambient or frozen (-18{sup 0}C) temperature was investigated by transmission electron microscopy (TEM). No significant change was found in muscle ultrastructure of shrimp meat irradiated at doses of 2 or 5 KGy and then stored at 4{sup 0}C for 0 and 8 days. However, in shrimps which were irradiated at ambient temperature at a dose of 10 KGy, the margin of A-band of the myofibrils in longitudinal sections exhibited an irregular zig-zag pattern. In cross section some myosin filaments in the A-band regions were missing. A possible interpretation of these results would be that 10 KGy gamma irradiation dose at ambient temperature depolymerized myosin in the A-band from the tail of thick filament. Actin damage was also observed in some cross sections. Irradiation ...

CERN Document Server

2009 has been an extraordinary year for gamma-ray pulsar astronomy and 2010 promises to be equally good. Not only have we registered an extraordinary increase in the number of pulsars detected in gamma rays, but we have also witnessed the birth of new sub-families: first of all, the radio-quiet gamma pulsars and later an ever growing number of millisecond pulsars, a real surprise. We started with a sample of 7 gamma-ray emitting neutron stars (6 radio pulsars and Geminga) and now the Fermi-LAT harvest encompasses 24 "Geminga-like" new gamma-ray pulsars, a dozen millisecond pulsars and about thirty radio pulsars. Moreover, radio searches targeted to LAT unidentified sources yielded 18 new radio millisecond pulsars, several of which have been already detected also in gamma rays. Thus, currently the family of ...

International Nuclear Information System (INIS)

Samples of vynil-benzene and vinyl acetate were irradiated with gamma rays from a sup(60)Co source. Viscosity analysis performed by using the method of Stokes showed an increase in the viscosity of the materials up to the total solidification for increased doses of gamma rays. This result characterized the formation of macromolecules of two thermal plastics, the poly (vinyl-benzene) and the poly (vinyl acetate). (author).

Energy Technology Data Exchange (ETDEWEB)

The X-ray spectra of {approx}200 AGN collected from Swift-BAT were analyzed to test the Unified Model for AGN. Specifically, the photon indices, high energy cutoffs, and reflection components of Sy1 and Sy2 were compared. Under the Unified Model, the photon indices and reflection components for Sy1 should be larger than Sy2 and the high energy cutoffs should be the same. Fitting a simple power law model to the sample spectra proved to be insufficient. The PEXRAV model fit the spectra of the Sy1 and Sy2 significantly better, indicating that a reflection component and/or high energy cutoff exists as the Unified Model expects. Using both the simple power law and PEXRAV models it was concluded that in the population studied, Sy1 had a larger photon index than Sy2, as expected by the Unified Model. For Sy1 and Sy2, the reflection components were found to be compatible, but given the large errors, this finding cannot be said to be evidence against the Unified Model. ...

International Nuclear Information System (INIS)

K#beta#-to-K#alpha# X-ray intensity ratios of Ti, V, Cr, and Co in pure metals and their disilicide compounds have been measured following excitation by 59.54 keV #gamma#-rays from a 200 mCi "2"4"1Am point-source. The K#beta#-to-K#alpha# intensity ratios of all these metals in the disilicide compounds are found to be less than the corresponding ratios for pure metals. Comparison of the measured K#beta#-to-K#alpha# intensity ratios for the disilicides and pure metals with the multiconfiguration Dirac-Fock calculations indicates increase of the 3d electron populations of Ti, V, Cr, and Co in the disilicides from their pure metal values suggesting the rearrangement of electrons between 3d and 4s states of the individual metal atom. This rearrangement is found to be opposite to that observed in our previously reported work on NiSi_2 and CuSi_2.

Energy Technology Data Exchange (ETDEWEB)

The INTEGRAL/SPI spectrometer was designed to observe the sky in the energy band of 20 keV to 8 MeV. The specificity of instrument SPI rests on the excellent spectral resolution (2.3 keV with 1 MeV) of its detecting plan, composed of 19 cooled germanium crystals; covering an effective area of 508 cm{sup 2}. The use of a coded mask, located at 1.7 m above the detection plan ensures to it a resolving power of 2.5 degrees. The aim of this thesis, begun before the INTEGRAL launch, is made up of two parts. The first part relates to the analysis of the spectrometer calibration data. The objective was to measure and check the performances of the telescope, in particular to validate simulations of the INTEGRAL/SPI instrument response. This objective was successfully achieved. This analysis also highlights the presence of a significant instrumental background noise. Whereas, the second part concentrates on the data analysis of the Vela region ...

Energy Technology Data Exchange (ETDEWEB)

The high spin fraction (HSF) of {sup 131}Te as a function of fragment emission angle has been determined in the 40 MeV alpha-particle induced fission of {sup 238}U using off-line gamma ray spectrometric technique. From the HSF the fragment average spin (J{sub av}) of fission product has been deduced using statistical model analysis. The J{sub av} value of {sup 131}Te is seen to remain nearly constant (10{Dirac_h}) from 90 deg. to 20 deg. On the other hand, the J{sub av} value of {sup 132}I from earlier work shows a drastic decrease (33%) from 11.4{Dirac_h} at 90 deg. to 7.6{Dirac_h} at 20 deg. . However, the yield weighted J{sub av} value of both the products show a decrease of 13%, which in close agreement with the value of 5-10% change from 90 deg. to 0 deg. in the results obtained from gamma ray multiplicity measurements. Thus the drastic difference in the change of fragment average spin (J{sub av}) ...

Energy Technology Data Exchange (ETDEWEB)

Neutron and gamma ray energy spectra were measured using an NE-213 scintillator at depths of 7.2, 15.2, and 22.2 cm in a tissue-equivalent phantom which was uniformly irradiated on one face by deuterium--tritium (DT) neutrons. Coupled neutron--gamma ray multigroup discrete-ordinates calculations were performed using semi-infinite slab geometry. These calculations were used to supplement the measured spectra below 1 MeV. Similar calculations were performed to study the perturbation in the phantom due to the detector. The measured and calculated spectra were used to determine the kerma distributions for neutrons and gamma rays at each location. The gamma radiation was determined to contribute more than 10% of the total dose at each depth. The calculated kerma also reveals that a knowledge of the gamma ...

Energy Technology Data Exchange (ETDEWEB)

Detailed level and decay schemes and the experimental reaction and decay data on which they are based are presented for nuclei with mass number A = 242; the experimental data are evaluated. Adopted values for level and ..gamma..-ray energies, ..gamma..-intensities, as well as other nuclear properties are given.

International Nuclear Information System (INIS)

(Jun 1972). United States Woolson, WA Las Vegas, Nev. 18 Jun 1972.

Energy Technology Data Exchange (ETDEWEB)

A number of concrete culverts used to retrievably store drummed, dry, radioactive waste at the Savannah River Site (SRS), were suspected of containing ambiguous quantities of transuranic (TRU) nuclides. These culverts were assayed in place for Pu-239 content using thermal and fast neutron counting techniques. High resolution gamma-ray spectroscopy on 17 culverts, having neutron emission rates several times higher than expected, showed characteristic gamma-ray signatures of neutron emitters other than Pu-239 (e.g., Pu-238, Pu/Be, or Am/Be neutron sources). This study confirmed the Pu-239 content of the culverts with anomalous neutron rates and established limits on the Pu-239 mass in each of the 17 suspect culverts by in-field, non-intrusive gamma-ray measurements.

International Nuclear Information System (INIS)

Gamma-ray spectrometric analysis was employed to determine the nuclides formed in thorium by neutron irradiation. Thorium sample was irradiated by neutron from a pure thermal neutron field, neutron field of Cd ratio of about 4, and epithermal neutron field, respectively. The former irradiation was carried out in a thermal neutron column provided for medical uses of neutrons, and the latters were done in the F-ring position of TRIGA II research reactor of Musashi Institute of Technology. The gamma-ray spectra were obtained and analyzed by employing a fully automatic gamma-ray analysis system named ''GAMA: giant frog:-SYSTEM'' developped by Musashi Institute of Technology. The formation of Pa-233 (U-233) was discussed quantitatively with respect to the difference of the neutron field. (author).

Science.gov (United States)

A series of experiments is to be made during the acceptance test program of the Fast Flux Test Facility (FFTF) to measure the gamma ray characteristics of the Fast Test Reactor (FTR) and to establish the performance characteristics of the reactor shield. These measurements are a part of the FFTF Reactor Characterization Program (RCP). Detailed plans have been developed for these experiments. During the initial phase of the Characteristics Program, which will be carried out in the In-Reactor Thimble (IRT), both active and passive measurement methods will be employed to obtain as much information concerning the gamma ray environment as is practical. More limited active gamma ray measurements also will be made in the Vibration Open Test Assembly (VOTA).

International Nuclear Information System (INIS)

This paper presents the analytical results of alcohols, esters and organic acids in sweet potato wine irradiated by #gamma#-rays. (author).

International Nuclear Information System (INIS)

Radiation induced polymerization of methylmethacrylate and copolymerization of styrene-acrylonitrile mixture in mamrase Carpinus betulus was carried out by means of #gamma#-ray, under different moisture levels and additives. Under all conditions the degree of polymerization was as high as 60%. No pronounced differences were observed in the kinetics of the polymerization of MMA either with moisture content of wood nor with kind and amount of additives. At high moisture (80% RH) content the dimensional stability of wood-PMMA was increased four fold as compared with untreated wood. The hardness increased about 100% for a weight conversion of monomer of about 30 to 40%. Hardness of this wood-polymer composite is comparable to that of the best noble woods in the world. (author).

Energy Technology Data Exchange (ETDEWEB)

In this report we present an update on the results from the Amanda-B10 detector which operated in 1997 at depths of 1500 to 2000 meters in the deep Antarctic ice. The goal of Amanda project is to search for extra-terrestrial neutrinos. As a precursor to such a search we have studied atmospheric neutrinos which act as a calibration source for the detector. The observation of atmospheric neutrinos at a rate consistent with Monte-Carlo predictions establishes Amanda-B10 as a neutrino telescope. The Amanda-B10 data has been searched for evidence of several classes of neutrinos and for magnetic monopoles. Searches for a diffuse high energy neutrino flux and for neutrinos in coincidence with gamma-ray bursts have been conducted. Preliminary data analyses show no excess of neutrinos has been found. (A.C.)

International Nuclear Information System (INIS)

Carcinogenesis is now generally recognized to be an important detrimental effect in man after low dose irradiation. The carcinogenic action of ionizing radiation is clearly demonstrated after exposure to relatively high doses (in excess of 0.5 Gy) but for lower dose levels reliable direct observations are not available. With the introduction of special protocols for the performance of large scale screening programs by mammography the average absorbed dose in glandular tissue in the average breast can be restricted to a value of 3 mGy per mammogram. The risk for tumor induction after exposure to these low doses can never be established from human epidemiology. In order to investigate the risk of repeated exposure to small dose of ionizing radiation the induction of mammary tumors has been investigated in rats of the WAG/Rij strain after single and fractionated irradiations with gamma-rays. (author). 8 refs., 3 figs.

International Nuclear Information System (INIS)

Black pepper, white pepper, red pepper, ginger and turmeric were irradiated with 10 MeV electrons from a linear accelerator to a dose of 100 kGy and radioactivity was measured in order to estimate induced radioactivity in the irradiated foods. Induced radioactivity could not be detected significantly by #gamma#-ray spectrometry in the irradiated samples except for spiked samples which contain some photonuclear target nuclides in the list of photonuclear reactions which could produce radioactivity below 10 MeV. From the amount of observed radioactivities of short-lived photonuclear products in the spiked samples and calculation of H_5_0 according to ICRP Publication 30, it was concluded that the induced radioactivity and its biological effects in the 10 MeV electron-irradiated natural samples were negligible in comparison with natural radioactivity from "4"0K contained in the samples. (author).

International Nuclear Information System (INIS)

Sentinel node (SN) scintigraphy for cervical and vulvar cancer guides the gynaecological oncologist in finding the metastatic lymph nodes during lymphadenectomy. The role of the surgical gamma probe in the sentinel node concept in gynaecological oncology is to localise (SN) both intra-operatively and transcutaneously. Intra-operative hand-held collimated gamma probes are increasingly used for detection of the sentinel lymph node. A comparative evaluation of handheld gamma probes: Neoprobe 1500, Europrobe, Gamma Finder, Gamma Ray Prospector GRP1 and GPR2 was performed using different detection methods. Laboratory tests were performed in which sensitivity, spatial resolution and angular sensitivity were evaluated. The results for each gamma probe were summarised and discussed. Awareness of a gamma probes capabilities and ...

International Nuclear Information System (INIS)

Reliable values of x-ray and gamma-ray attenuation coefficients of elements and compounds are required in spectrometry as well as in many other scientific, engineering and medical disciplines involving photon radiation

Energy Technology Data Exchange (ETDEWEB)

The {rvec n} + p {yields} d + {gamma} experiment under construction at LANSCE studies the weak interaction between neutrons and protons. The experiments will measure the directional dependence of the parity-violating {gamma}-ray asymmetry, A{sub {gamma}}, in the polarized cold neutron capture by para-hydrogen. The goal is to measure A{sub {gamma}} with uncertainty of 0.5 x 10{sup -8}, 10% of its predicted value. A{sub {gamma}} primarily isolates the {Delta}I = 1 component of the hadronic weak interaction and thus will determine the long-range weak pion-nucleon coupling constant H{sub {pi}}{sup 1}. The experiment is carefully designed for the LANSCE pulsed spallation neutron source to achieve the proposed statistical precision and to control systematic errors. We discuss the experiment and its status.

International Nuclear Information System (INIS)

Chemical effects of L X-ray intensity ratios in niobium and molybdenum compounds were studied by electron and proton bombardments. L_#gamma#_1 X-rays which involve transition of 4d electrons of the valence shell were found to be sensitive to the chemical environment. The L_#gamma#_1/L_#beta#_1 X-ray intensity ratio increased with an increase of the 4d electron occupation of niobium or molybdenum in niobium or molybdenum compounds, showing that the chemical effects can be ascribed to the 4d electron behavior of the metallic atom in its compounds. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The proposed short wavelength coherent light source driven by the SLAC 3 km linac might be used to induce transitions between nuclear isomeric states. If an isotope were found with energetically adjacent isomeric states, one short-lived and one long-lived, and it were possible to separate and concentrate the long-lived species, and other nuclear and solid-state parameters were favorable, it might be possible to convert sufficient population to the short-lived state to realize {gamma}-ray lasing. Even if the x-ray intensity were insufficient, study of such driven transitions would be quite valuable.

International Nuclear Information System (INIS)

We calculate the cross sections for the single production of doubly charged dileptons, both scalar and vector, at e"+e"-, e#gamma#, and #gamma##gamma# colliders at #sq root#s =500 GeV and 1 TeV. The e#gamma# mode is by far the most promising---dileptons whose coupling is as weak as #approx#10"-"4#alpha#_e_m can be observed, for masses virtually up to the kinematic limit. Dileptons of mass up to #sq root#s can also be seen in e"+e"- and #gamma##gamma# colliders, for couplings of order #alpha#_e_m. In all three colliders, most of the cross section comes from events in which the only particles detected are e"-e"- (or #mu#"-#mu#"- or #tau#"-#tau#"-), the decay products of the dilepton, yielding an unmistakable experimental signature.

Energy Technology Data Exchange (ETDEWEB)

We perform an optimal-observable analysis of the final charged-lepton/b-quark momentum distributions in {gamma}{gamma}{yields}t t-bar {yields}lX/bX for various beam polarizations in order to study possible anomalous t t-bar {gamma}, tbW and {gamma}{gamma}H couplings, which could be generated by SU(2) x U(1) gauge-invariant dimension-6 effective operators. We find optimal beam polarizations that will minimize the uncertainty in determination of those non-standard couplings. We also compare e e-bar and {gamma}{gamma} colliders from the viewpoint of the anomalous-top-quark-coupling determination.

Science.gov (United States)

New sets of cross sections for the production of krypton isotopes from targets of Rb, Sr, Y, and Zr were constructed primarily on the bases of experimental excitation functions for Kr production from Y. These cross sections were used to calculate galactic-cosmic-ray and solar-proton production rates for Kr isotopes in the moon. Spallation Kr data obtained from ilmenite separates of rocks 10017 and 10047 are reported. Production rates and isotopic ratios for cosmogenic Kr observed in ten well-documented lunar samples and in ilmenite separates and bulk samples from several lunar rocks with long but unknown irradiation histories were compared with predicted rates and ratios. The agreements were generally quite good. Erosion of rock surfaces affected rates or ratios for only near-surface samples, where solar-proton production is important. There were considerable spreads in predicted-to-observed production rates of /sup 83/Kr, ...

Energy Technology Data Exchange (ETDEWEB)

We present the efficient technique to extract the signal of the intermediate mass Higgs boson from the backgrounds at future {gamma}{gamma} colliders. For a clear Higgs detection, it is important to fit the original electron accelerator energy depending on the Higgs mass, to set the polarization of the photon beams and to apply the efficient b quark tagging method. we demonstrate the extraction of information of Higgs parameters and the new physics from the observable physical quantities. It is clearly shown that a future {gamma}{gamma} collider will have a rich potential for study on the new physics, as well as the Higgs physics. (author).

CERN Document Server

In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $\\gamma$ ray spectra with EGRET data in all sky regions. It also gives consistent results of the diffuse $\\gamma$ ray longitude and latitude distributions. Further the results for B/C, $^{10}$Be/$^9$Be, proton, electron and antiproton spectra are also consistent with cosmic ray measurements. In the model we have taken a universal proton spectrum throughout the Galaxy without introducing large fluctuation for the proton energy loss is negligible. The dark matter annihilation signals are `boosted' after taking the contribution from subhalos into account. Another interesting feature of the model is that it gives better description of the diffuse ...

International Nuclear Information System (INIS)

Estimations on the somatic and genetic effects of small doses of ionizing radiations in Man have been proposed by the Advisory Committee on the Biological Effects of Ionizing Radiation, set up by the U.S. National Academy of Sciences. They have been published in an important report, issued in 1972, from which we briefly analyze here the Chapter dealing with the somatic effects. Small doses of raditions are expected to promote only carcinogenic effects. After a rapid survey of the human experience on which the estimations are based, as regards the latent period of cancers, the plateau region (period of high risk) and the absolute and relative risk expressed per rem, per 10"6 persons, per year, for leukaemia (having the highest risk) and for the ''other cancers''. These estimations were obtained by linear extrapolation to the 1 rem level from observations made after irradiation at relatively high dose levels and much higher dose-rates. This extrapolation procedure, ...

International Nuclear Information System (INIS)

We consider single production of leptoquarks (LQ's) at e"+e- and #gamma##gamma# colliders, for two values of the center-of-mass energy: #sq root#s =500 GeV and 1 TeV. We find that LQ's which couple within the first generation are observable for LQ masses almost up to the kinematic limit, both at e"+e- and #gamma##gamma# colliders, for an LQ coupling strength equal to #alpha#_e_m. The cross sections for single production of second- and third-generation LQ's at e"+e- colliders are too small to be observable. In #gamma##gamma# collisions, on the other hand, second-generation LQ's with masses much larger than #sq root#s /2 can be detected. However, third-generation LQ's can be seen at #gamma##gamma# colliders only for masses at most #approx# #sq root#s /2, making their observation more probable via the pair production mechanism.

Energy Technology Data Exchange (ETDEWEB)

The effect of severe plastic deformation by cold high pressure torsion (HPT) on radio frequency (RF) plasma nitriding of pure iron, as well as St2K50 and X5CrNi1810 steels was investigated. Nitriding was carried out for 3 h in a nitrogen atmosphere at a pressure of 10{sup -5} bar and temperatures of 350 and 400 deg. C. Nitrided specimens were analysed by scanning electron microscopy (SEM), X-ray diffraction and micro hardness measurements. It was found that HPT enhances the effect of nitriding leading almost to doubling of the thickness of the nitrided layer for pure iron and the high alloyed steel. The largest increase in hardness was observed when HPT was combined with RF plasma nitriding at 350 deg. C. In the case of pure iron, the X-ray diffraction spectra showed the formation of {epsilon} and {gamma}' nitrides in the compound layer, with a preferential formation of ...

International Nuclear Information System (INIS)

New measurements of relative gamma-ray emission probabilities in the decay of "1"0"1Mo and "1"0"1Tc are reported. Previously published conversion-electron data have been used along with the gamma-ray data to formulate self-consistent decay schemes. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Samples of some domestic and imported food products of nutritive importance to both the child population and the adult population in Nigeria were collected and analysed in order to determine their radionuclide contents. The samples were collected from open markets in major commercial cities in the country. Gamma-ray spectrometry was employed in the determination of the radionuclide contents in the products. The gamma-ray peaks observed with reliable regularity in all the samples analysed belong to naturally occurring radionuclides, namely {sup 226}Ra, {sup 228}Th and {sup 40}K. The activity concentrations of these radionuclides in both the domestic and imported products were observed to be not significantly different. Essentially radioactive elements such as {sup 137}Cs were not detected in any of the samples. The non-detection of {sup 137}Cs in the imported products may be attributed to the suitably ...

International Nuclear Information System (INIS)

Pregnant Swiss albino mice of 18 days post conception were exposed to 0.80 Gy, 0.40 Gy and 0.20 Gy of gamma rays from a Cobalt-60 source at different dose rates (.0584 Gy/min and .00091 Gy/min). Post irradiation variations in the cell population of crypts and villus of jejunum were studied in the F_1-generation at 1 day, 3 day and 1,2,4,6 and 12 weeks of post-partum age. In all the exposure groups at 1 day post-partum age, crypts show a decrease in total cells, mitotic figures and goblet cells on one hand and an increase in PNNC on the other hand in comparison to coeval controls. At this interval a decrease in the number of total cells as well as goblet cells/villus column was also noticeable. Dead cells which were prominently seen in crypts were totally absent in villi. The first signs of recovery can be observed on day 3 p.p. when total cell population, mitotic activity and goblet cells of crypt registered an increase ...

Energy Technology Data Exchange (ETDEWEB)

Carbide reactions occurring in a precipitation-hardening gamma/gamma-prime Ni-Cr alloy during prolonged high-temperature aging are investigated experimentally. It is found that the decomposition of primary MC carbides, which is accompanied by the precipitation of M23C6 particles, may lead to void nucleation and growth. The effect of carbide transformations on the residual properties of the material at temperatures above the equicohesion temperature is observed at the late stages of aging only. 6 references.

Energy Technology Data Exchange (ETDEWEB)

Using Gammasphere data on prompt gamma rays from spontaneous fission of 252Cf, we propose energy-level schemes for 110,111,112, & 113Rh (Z=45). The fission-gamma data complement earlier studies of others on beta decay of fission products in that prompt fission gammas mainly populate yrast or near-yrast levels, while beta decay populates lower-spin levels. For the odd-A rhodium nuclei studied here, their ground bands and collective sidebands are compared with model calculations using triaxial-shaped nucleus with one odd quasi-proton. The energies and E2 transition rates are best fit by a shape slightly to the prolate side of maximum triaxiality, namely, gamma = 28 deg. The model calculations also show a K=1/2+ band with energies not in good agreement with a corresponding experimental band. The experimental 1/2+ band is regarded as an intruder band from a prolate-driving proton ...

Energy Technology Data Exchange (ETDEWEB)

Because the number of neutrons and gamma rays and the energy spectrum of particles from spontaneous fission are well characterized for {sup 252}Cf, it can be used as a timed source of fission neutrons and gamma rays. The first such usage incorporated a {sup 252}Cf source into gas scintillators. This paper describes a timed source of neutrons and gamma rays made by depositing {sup 252}Cf on one electrode of a parallel plate ionization chamber that can then be used for determining detection-system characteristics. The emission time of neutrons from spontaneous fission has also been determined by recording the emission time of prompt gamma rays from a {sup 252}Cf source (not incorporated into a detector) adjacent to the surface of a solid or liquid scintillator. This well characterized source of neutrons can thus be used as ...

International Nuclear Information System (INIS)

The gamma scanning system which is installed in IMEF is the equipment obtaining the gamma ray spectrum from irradiated fuels. This equipment could afford the useful data relating spent fuels like as burn-up measurements. We describe the specifications of the equipment and its accessories, and also described its operation procedure so that an operator can use this report as the operation procedure. (author). 1 tab., 11 figs., 11 refs.

Energy Technology Data Exchange (ETDEWEB)

The crabbing of an incident photon beam from a laser, and the electron beam with which it interacts at the conversion point, is shown to have the same efficiency as in head-on Compton scattering, but with the advantages of a crossing geometry. The resulting {gamma}-ray beam is also crabbed, which allows for a crossing collision point, while maintaining the luminosity at the same value it would have in a head-on collision. ((orig.)).

Science.gov (United States)

The availability of rice, gamma -irradiated up to 4.6 x 10/sup 4/ and 3.5 x 10/sup 5/r for koji was studied. The enzyme activities of koji of the steamed samples were stronger than the unirradiated rice in amylase and protease. The sensory test on the once-steamed irradiated rice was almost the same as the twice-steamed unirradiated rice. (OID)

International Nuclear Information System (INIS)

Using high-resolution y-rays spectrometry, the natural radioactivity of 14 samples of natural and o manufactured Egyptian building materials have been investigated. The samples were collected from local market and construction sites. From the measured gamma-ray spectra, specific activities were determined. The radium equivalent activity in each sample was estimated. Radiological evaluations of these materials indicate that all materials meet the external gamma-ray dose limitation. Calculation of concentration indices by assuming a Markkanen room model is constructed from these materials, to find the excess gamma-ray dose taken over that received from the outdoors. The Austrian Standard ONORM S 5200 is used in testing the building materials.

Energy Technology Data Exchange (ETDEWEB)

Direct current (DC) glow discharge plasma nitriding was carried out on three selected surface-roughened AISI 304 stainless steel samples at 833 K under 4 mbar pressures for 24 h in the presence of N{sub 2}:H{sub 2} gas mixtures of 50 : 50 ratios. After plasma nitriding, the phase formation, case depth, surface roughness, and microhardness of a plasma-nitrided layer were evaluated by glancing angle x-ray diffractogram, optical microscope, stylus profilometer, and Vickers microhardness tester techniques. The case depth, surface hardness, and phase formation variations were observed with a variation in initial surface roughness. The diffraction patterns of the plasma-nitrided samples showed the modified intensities of the {alpha} and {gamma} phases along with those of the CrN, Fe{sub 4}N, and Fe{sub 3}N phases. Hardness and case depth variations were observed with a variation in surface roughness. A ...

Energy Technology Data Exchange (ETDEWEB)

Apoptosis is a pattern of cell death involving nuclear pycnosis, cytoplasmic condensation, and karyorrhexis. Apoptosis induced by continuous irradiation with gamma rays (externally given by a 137Cs source) or with beta rays (from tritiated water injected ip) was quantified in the crypts of two portions of mouse bowel, the small intestine and descending colon. The time-course change in the incidence of apoptosis after each type of radiation could be explained on the basis of the innate circadian rhythm of the cells susceptible to apoptotic death and of the excretion of tritiated water (HTO) from the body. For 6-h continuous gamma irradiation at various dose rates (0.6-480 mGy/h) and for 6 h after injection of HTO of various radioactivities (0.15-150 GBq per kg body wt), the relationships between dose and incidence of apoptosis were obtained. Survival curves were then constructed from the curves for dose ...

International Nuclear Information System (INIS)

Most general tbW couplings were investigated in the process #gamma##gamma# #-># tt-bar #-># l"#+-#X for unpolarized photon beams. The double angular and energy distribution of the lepton was calculated and an optimal-observable analysis on it was carried out for the SM tt-bar production mechanism. It was also shown that the leptonic angular distribution is insensitive to non-standard tbW vertex. That means that observation of non-standard effects indicates existence of some new physics in the production part.

CERN Document Server

We investigate the effect of anomalous gamma-W-W couplings in e-gamma --> nu W through the angular and energy spectrum of the secondary leptons. Within the narrow-width approximation, a semi-analytical study of the secondary lepton energy-angle double distribution is considered. Utility of observables derived from this is demonstrated by considering the anomalous coupling, delta-kappa-gamma. Results of our investigation for typical ILC machine considered at Ecm = 300-1000 GeV re-affirms potential of this collider as a precision machine.

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It is shown that a cosmic gamma-ray telescope made of a multilayer silicon tracker and a imaging CsI calorimeter, is capable of identifying cosmic ray nuclei. The telescope charge resolution is estimated around 4% independently of charge. Simulation methods are used to determine the telescope properties for nuclei detection.

International Nuclear Information System (INIS)

The advance in the analysis of very small amount (<= 1#alpha#/cm"2h) of #alpha#-emitters in the cited materials is reviewed. The review, for which 75 references are listed, covers the period from January, 1978, to June, 1982. The use of #alpha#-ray counting, #alpha#-ray spectrometry, #gamma#-ray spectrometry, neutron activation analysis and mass spectrometry is discussed, and their relative merit and limitation are outlined. (J.P.N.).

International Nuclear Information System (INIS)

Several configurations of moderating and shielding materials have been designed and measured on the LVR-15 reactor for boron neutron capture therapy (BNCT) purposes. To determine the neutron and gamma ray space-energy distributions in the cylindrical geometry, the two-dimensional code DOT with the coupled neutron-gamma data library DLC-36 was used. The experimental verification of the beam parameters was performed in the LVR-15 reactor thermal column empty space with layers of graphite, aluminium, alumina, lead and bismuth. Attention was paid to establishing techniques and instrumentation for monitoring the neutron and gamma ray dose and beam quality. The thermal and epithermal flux densities were measured by activation foils, the neutron spectrum was determined with a Bonner spectrometer and gamma ray background with a scintillation ...

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The detection efficiency of gamma scanning system in irradiated materials examination facility has been measured. Gamma-ray sources used in this experiment are Cs-Co standard sources a PWR spent fuel rod in which {sup 134}Cs and {sup 154}Eu peaks are clearly identified in the energy region of 500 to 1,600 keV. The distance between source and detector is about 1.6 m. A slit type collimator with 3 mm-width window and 30 mm-thick lead block are installed between source and detector. The detector is a HPGe detector. This equipment is mainly used in gamma scanning of irradiated nuclear fuel. The measured detection efficiency seems to be 1.89 x 10{sup -6} % for 1 MeV gamma-ray. With these results the activities of unknown sources could be measured. This results are expected to be used in the measurement of the absolute distribution of gamma emitting nuclides in nuclear fuel.

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A theoretical model is developed to explain variations in airborne gamma-ray measurements over a calibration range near Ottawa, Ontario. The gamma-ray flux from potassium and the thorium decay series showed an expected decrease with increasing soil moisture. However, the gamma-ray flux from the uranium decay series was highest in the spring when the ground was water-saturated and even covered with snow. These results are explained through the build-up of radon and its associated gamma-ray-emitting decay products in the clay soil of the calibration range with increasing soil moisture. Similar results were found from airborne measurements over other clay soils. However, measurements over sandy soils showed that the count rates from all three radio elements increased with decreasing soil moisture. This difference between soil types was attributed to the lower radon emanation of the more coarse-grained ...

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Possible anomalous top-quark couplings induced by SU(2)xU(1) gauge-invariant dimension-6 effective operators were studied in the process of ttbar productions and decays at polarized {gamma}{gamma} colliders. Two CP-violating asymmetries, a linear-polarization asymmetry and a circular-polarization asymmetry, were computed including both non-standard ttbar{gamma} and {gamma}{gamma}H couplings. An optimal-observable analysis for the process {gamma}{gamma}{yields}ttbar{yields}l{sup {+-}} was performed in order to estimate the precision for determination of all relevant non-standard couplings, including the anomalous tbW coupling.

International Nuclear Information System (INIS)

local peanut cultivars Giza 4 and Giza 5 were exposed to different doses ( 50,100,150,200,250 and 300 Gy)to Co "6"0 gamma ray source . all irradiated materials were cultivated to give the M_1 and M_2 generation , then high yielding mutants were selected from the M_2 generation and cultivated separately to give the M_3 generation. some yield component traits were measured for the three generations (M_1,M_2 and M_3) and M_3 families.variations observed in these traits were attributed to genetic factors. the M_3 selected mutants were artificially infected by aspergillus flavus L spores (aflatoxins-B1 and B2 groups-producer strain). aflatoxin concentrations were estimated and the analysis showed that aflatoxin concentrations in seeds of the M_3 selected mutants from cultivar Giza 4 were higher than those in seeds of the M3 mutants selected from cultivar Giza 5. however, the concentration of aflatoxin increased when the yield ( ...

Energy Technology Data Exchange (ETDEWEB)

The excitation function of the {sup 64}Ni({alpha},p){sup 67}Cu reaction was measured from threshold up to 24 MeV in order to investigate the possibility of production of the {beta}{sup -}-emitting therapeutic radioisotope {sup 67}Cu (T{sub 1/2}=61.9 h). Two stacks of thin metallic self-supporting foils of {sup 64}Ni (enrichment 77.8%) prepared by electrolytic deposition were irradiated by {alpha}-particle beams. The radioactivity was determined via HPGe detector {gamma}-ray spectrometry. Some {sup 67}Ga activity (which emits the same {gamma}-rays as {sup 67}Cu), formed via the {sup nat}Cu({alpha},x){sup 67}Ga process on trace copper impurity in the Ni foils, was also observed. Corrections were done for {sup 67}Ga activity contribution and for the {sup 67}Cu activity escape fraction from the thin Ni-foil. The maximum cross section of the {sup 64}Ni({alpha},p){sup 67}Cu reaction amounts to 34 mb at 22 MeV. The experimental ...

International Nuclear Information System (INIS)

The Polarized Gamma-ray Observer (PoGOLite) is a balloon-borne instrument that will measure gamma-ray polarization in the energy range 25-80 keV from astronomical sources such as pulsars, accretion discs and jets from active galactic nuclei. The two additional parameters provided by such observations, polarization angle and degree, will allow these objects to be studied in a new way, providing information about their emission mechanisms and geometries. The instrument measures azimuthal scattering angles of photons within a close packed array of phoswich detector cells (PDCs) based on coincident detection of Compton scattering and photoelectric absorption. Each PDC comprises three different scintillating components and combines photon detection, active collimation and bottom anticoincidence into one single unit. The three parts are viewed by a photomultiplier tube (PMT) and pulse shape discrimination is ...

Energy Technology Data Exchange (ETDEWEB)

The measurement of level in the liquid nitrogen vessel has been carried out by the weight conversion method using weigher or by putting directly a stick in the vessel. On a large CE tank, the pressure difference was read by manometer. These methods can not be used when the vessel does not put on the weigher or the pipe for manometer is stopped. We noticed the interaction between radiation ({gamma}-ray) and substance and applied it to determine the liquid nitrogen level. The results proved it the easy method for measurement of the level in the large CE tank. Cesium 137 ({gamma}-ray energy: 662 keV) was used as the radiation source. {gamma}-ray transmission dose was determined by GM survey meter. The liquid nitrogen level could be determined by using the change of the transmission dose with amount of liquid nitrogen. (S.Y.)

International Nuclear Information System (INIS)

The inverse Compton scattering between positron bunches and the Free Electron Laser (FEL) of the SuperAco storage ring generates a collimated and tunable gamma-ray beam. The use of the FEL instead of a conventional laser, automatically provides the transverse alignment and synchronisation of the electron and optical beams. The Super-ACO FEL is operated in the 300-430 nm range at 800 MeV with a high repetition rate (8 MHz) and an average transmitted power of 300 mW at 350 nm. High energy gamma rays of 35 MeV are produced with a rate of 1.5 10 7 photons/second and good monocromaticity (about 10%). Applications of the SuperAco FEL installation for diamond irradiation and biological studies are envisaged. (author)

Energy Technology Data Exchange (ETDEWEB)

The ASFIT (Anisotropic Source-Flux Iteration Technique) code was first developed in India about 1970 to solve the radiation transport equation represented in the form of coupled integral equations separating the spatial and energy-angular transmissions. The ASFIT code uses a nodal structure in the wavelength [lambda] domain in Compton units (CU) rather than in the energy domain. The ASFIT-VARI code is the latest version available from the Radiation Shielding Information Center. It incorporates variable dimensioning and has been adapted for use on MS-DOS personal computers using the Ryan-McFarland or Microsoft Version 5.0 FORTRAN compilers. While earlier versions used point cross sections (well suited for gamma-ray transport), the present version also allows multigroup cross sections for neutron and coupled neutron-gamma-ray transport.

Energy Technology Data Exchange (ETDEWEB)

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the only major protection to astronauts from harmful exposure. Unlike low-linear energy transfer (LET) {gamma} or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure, since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak. The Bragg curve does not necessarily represent the biological damage along the particle traversal, and the 'biological Bragg curve' is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. Here we used a unique irradiation geometry to measure the biological response across the Bragg curve in human fibroblasts exposed to 577MeV/nucleon incident Fe ions ...

International Nuclear Information System (INIS)

Personnel radiation monitoring is essential to the operation of any nuclear facility and work in this area continues to strive for an accurate determination of personnel dose. In particular recent attention has been focused upon the need to improve the accuracy of neutron dosimetry, mainly because of their high Relative Biological Effectiveness. In this work the feasibility of using the NE-213 liquid scintillation detector as an efficient neutron/#gamma# ray radiation monitor is demonstrated. Derivative method spectrum unfolding used in MATXUF for on-line analysis of fast neutron spectra has also been applied to real time #gamma# spectrum unfolding (MATXUF2), making possible simultaneous on-line monitoring of both fast neutrons and gammas. To eliminate the negative fluxes in the unfolded #gamma# spectra created by the photopeak-Compton edge combination in the plateau portion of the ...

Energy Technology Data Exchange (ETDEWEB)

In the investigations reported here, a helium-jet/tape-transport system was used for the rapid transfer of fission products to a low-background environment where their aggregate beta and gamma-ray spectra were measured as a function of delay time after neutron induced fission of {sup 235}U, {sup 238}U and {sup 239}Pu. Beta and gamma-ray energy distributions have been deduced for delay times as short as 0.2 s and extending out to 100,000s. Instrumentation development during the initial phase of the project included: (1) assembly and characterization of a NaI(Tl) spectrometer for determining aggregate gamma-ray energy distributions, (2) development and characterization of a beta spectrometer (having excellent gamma-ray rejection) for measuring aggregate beta-particle energy distributions, (3) assembly and characterization of a Compton-suppressed HPGe spectrometer for determining ...

International Nuclear Information System (INIS)

At the RIKEN-RAL Muon Facility, ?- to ? sticking K? X-rays were observed for the first time taking advantage of the pulsed beam structure. The precision of the present measurements was insufficient to distinguish between theoretical models, however the observed K?/K? X-ray intensity ratio tends to be smaller than most of these theoretical predictions.

International Nuclear Information System (INIS)

Low-lying nuclear energy levels in "1"1"0In and "1"1"2In were determined from de-excitation #gamma#-rays produced with "1"0"7Ag(#alpha#,n#gamma#)-"1"1"0In, "1"0"8Pd("6Li,4n#gamma#)"1"1"0In, "1"0"9Ag(#alpha#,n#gamma#)"1"1"2In and "1"1"0Pd("6Li,4n#gamma#)"1"1"2In reactions. In addition, the "1"1"4In energy level structure was investigated with the "1"1"0Pd("7Li,3n#gamma#)"1"1"4In reaction. Properties of de-excitation #gamma#-rays were determined from #gamma#-#gamma# coincidence, excitation, and angular distribution measurements conducted with Ge(Li) and Ge(intr.) #gamma#-ray detectors. A sequence of intraconnected levels in each of "1"1"0,"1"1"2,"1"1"4In were assigned to the (#pi#g"-"1/sub 9/2/, #nu#h/sub 11/2/) configuration. For the "1"1"0,"1"1"2,"1"1"4In energy level schemes a model calculation has ...

Energy Technology Data Exchange (ETDEWEB)

K{beta}-to-K{alpha} X-ray intensity ratios of Ti, Cr, Fe and Co in pure metals and in Cr{sub 0.26}Fe{sub 0.74}, Cr{sub 0.80}Co{sub 0.20} and Ti{sub 0.80}Cr{sub 0.20} alloys have been measured following excitation by 59.54 keV {gamma}-rays from a 7400 MBq (200 mCi) {sup 241}Am point-source. The valence electronic structure of Ti, Cr, Fe and Co in the samples have been evaluated by the comparison of the measured K{beta}-to-K{alpha} intensity ratios with the results of multiconfiguration Dirac-Fock calculations performed for various electronic configurations of these metals. The 3d-electron populations obtained for pure metallic Ti, Cr, Fe and Co agree well with the results of band structure calculations of Papaconstantopoulos (Handbook of band structure of elemental solids, Plenum Press, New York, 1986). Our analysis indicates significant increase of 3d-electron population of Ti, Cr and Fe in the alloys with respect to the pure metals, except for ...

International Nuclear Information System (INIS)

K#beta#-to-K#alpha# x-ray intensity ratios of Fe and Ni in pure metals and in Fe_xNi_1_-_x alloys (x=0.20, 0.50, 0.58) exhibiting similar crystalline structure have been measured following excitation by 59.54 keV #gamma# rays from a 200 mCi "2"4"1Am point source to understand why the properties of the Fe_xNi_1_-_x (x=0.2) alloy are distinct from other alloy compositions. The valence electronic structure of Fe and Ni in the samples has been evaluated by comparing the measured K#beta#-to-K#alpha# intensity ratios with the results of multiconfiguration Dirac-Fock calculations. Significant changes in the 3d electron population (with respect to the pure metal) are observed for Fe and Ni for certain alloy compositions. These changes can be explained by assuming rearrangement of electrons between 3d and (4s,4p) band states of the individual metal atoms. It has been found that the valence electronic structure ...

International Nuclear Information System (INIS)

Terminal-differential algorithm for identification of local nonhomogeneities in items under control is developed on the basis of measurements of X-ray or gamma-radiation weakening. The algorithm may be applied by developing radiation schemes of nondestructive control, identifying inadmissible inclusions in the object under study

International Nuclear Information System (INIS)

Bulgarian ... Orig. Title Vliyanie na gama-lychite vyrkhu spirokheti ot vida Borrelia anserina, Sakharoff, 1891. Chast 2. Promeni v antigenniya stroezh.

International Nuclear Information System (INIS)

A brief letter attempts to justify the assumption in an earlier paper of an isotropic distribution of environmental gamma rays incident on humans. A second letter from the original authors responds to this in yet more detail. (UK).

International Nuclear Information System (INIS)

Development of techniques for separating isomeric nuclides is important to the investigation of schemes for gamma-ray lasers. In preparation for an experiment to separate 10_1_4 atoms of the /sub 197m/Hg (299 keV, tau/sub 1/2/ = 24 hours) isomer, we report isotopically selective resonance ionization of mercury atoms. This has been accomplished by three-step excitation via the 6_3P"1 and 8_1S"0 excited states, using three collinear pulsed laser beams of 254, 286, and 532 nm wavelengths from a Nd:YAG and two dye lasers. These beams were passed through a closed mercury-vapor cell containing electrostatic plates to which the ions were drawn. Ion current and fluorescent radiation were measured as a function of laser frequency. Hyperfine structures for the 254- and 286-nm transitions were observed.

Energy Technology Data Exchange (ETDEWEB)

The large uranium fission cross section leading to iodine and the behaviour of this element in the cladding tube during energy production and afterwards during waste storage is a crucial problem, especially for {sup 129}I which is a very long half-life isotope (T=1.59 x 10{sup 7} yr). Since a combined external and internal oxidation of the zircaloy cladding tube occurs during the reactor processing, iodine diffusion parameters in zirconia are needed. In order to obtain these data, stable iodine atoms were first introduced by ion implantation into zirconia with an energy of 200 keV and a dose equal to 8 x 10{sup 15} at cm{sup -2}. Diffusion profiles were measured using 3 MeV alpha-particle Rutherford backscattering spectrometry at each step of the annealing procedure between 700 C and 900 C. In such experiments a reduced iodine concentration was observed, which correlated to a diffusion-like process. Similar analysis has been performed using radioactive {sup 131}I ...

International Nuclear Information System (INIS)

We discuss the prospects for bounding and perhaps even measuring quantum gravity effects on the dispersion of light using the highest-energy photons produced in gamma-ray bursts (GRBs) measured by the Fermi telescope. These prospects are brighter than might have been expected, as in the first ten months of operation, Fermi has so far reported eight events with photons over 100 MeV seen by its Large Area Telescope. We review features of these events which may bear on Planck-scale phenomenology, and we discuss the possible implications for alternative scenarios for in-vacua dispersion coming from breaking or deforming of Poincare invariance. Among these are semiconservative bounds (which rely on some relatively weak assumptions about the sources) on subluminal and superluminal in-vacuo dispersion. We also propose that it may be possible to look for the arrival of still higher-energy photons and neutrinos from GRBs with energies in the range 1014-1017 eV. In some ...

International Nuclear Information System (INIS)

The survivability of the final optic, which must sit in the line of sight of high-energy neutrons and gamma rays, is a key issue for any laser-driven inertial fusion energy (IFE) concept. Previous work has concentrated on the use of reflective optics. Here, we introduce and analyze the use of a transmissive final optic for the IFE application. Our experimental work has been conducted at a range of doses and dose rates, including those comparable to the conditions at the IFE final optic. The experimental work, in conjunction with detailed analysis, suggests that a thin, fused silica Fresnel lens may be an attractive option when used at a wavelength of 351 nm. Our measurements and molecular dynamics simulations provide convincing evidence that the radiation damage, which leads to optical absorption, not only saturates but that a 'radiation annealing' effect is observed. A system-level description is provided, including ...

CERN Document Server

One class of gravitational wave signals LIGO is searching for consists of short duration bursts of unknown waveforms. Potential sources include core collapse supernovae, gamma ray burst progenitors, and the merger of binary black holes or neutron stars. We present a density-based clustering algorithm to improve the performance of time-frequency searches for the such gravitational-wave bursts when they are extended in time and/or frequency. We have implemented this algorithm as an extension to the QPipeline search for bursts, which currently determines the statistical significance of events based solely on the peak significance observed in minimum uncertainty regions of the time-frequency plane. Density based clustering improves the performance of such a search by considering the aggregate significance of arbitrarily shaped regions in the time-frequency plane and rejecting the isolated minimum uncertainty features expected ...

Energy Technology Data Exchange (ETDEWEB)

Inelastic scattering of 180 MeV {pi}{sup +} and {pi}{sup {minus}} from {sup 52}Cr shows an angular distribution for the 2{sub 2}{sup +} state at 2.96 MeV that differs greatly from the usual {ital L} = 2 shapes for 2{sup +} states. This state is perhaps the only case from pion-inelastic scattering in which standard distorted-wave impulse approximation models (including multistep and single-step responses) fail to reproduce the measured angular distribution. Furthermore, this unique excitation has been shown to have the features expected of a seniority-four proton excitation yet the pion data show charge symmetry. While coupled-channel calculations are not able to reproduce the pion data, they do agree with the shape observed for 42 MeV {alpha} particle scattering to this state, but the magnitude of the {alpha} scattering data is not consistent with a collective model and known {gamma} ray deexcitations. Scattering to the ...

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We present the effects of heavy CP-even (H) and CP-odd (A) Higgs bosons on the production cross section of the process {gamma}{gamma}{yields}tt at the energy around the mass poles of the Higgs bosons. It is found that interference between H and A with small mass gap, as well as the ones between Higgs bosons and continuum, contributes to the cross section, if the photon beams are polarized and if we observe the helicity of the top quarks. It is demonstrated in the framework of the minimal supersymmetric extension of the standard model that the H and A contributions can be sizable at future {gamma}{gamma} colliders for small values of tan {beta}. The methods to measure the CP-parity of the Higgs boson are also presented. The statistical significance of detecting the Higgs signals and measuring the Higgs CP-parity is evaluated. (orig.)

International Nuclear Information System (INIS)

A new acquisition and evaluation procedure has been introduced for the measurement of time-dependent processes in gamma-ray spectrometry, in order to extract more information, including half-lives, from the data recorded during acquisition and to enable a more comprehensive analysis of the results. These advanced, off-line data evaluation techniques improve the selectivity and the background subtraction and make it possible to estimate the important analytical parameters (e.g., half-lives) more accurately than with the usual decay curve fitting method. (author)

International Nuclear Information System (INIS)

Two experiments are currently underway to measure the single-particle weak mixing matrix element for the 1064 KeV transition in "2"0"7Pb. One experiment measures the circular polarization of the 1064 KeV gamma ray emitted from an unpolarized source, while the other experiment measures the forward-backward asymmetry of gamma rays emitted from a polarized source. Analysis of the first set of polarized source data yields an upper limit of 46 eV for the single-particle weak mixing matrix element. copyright 1995 American Institute of Physics.

International Nuclear Information System (INIS)

Energy conservation and local energy deposition are investigated in the context of coupled-particle (i.e., neutrons, gamma rays, and charged particles) transport analysis. For charged particles, the concept of group splitting the 1 = 0 transfer matrix to ensure both particle and energy conservation is introduced. Although these procedures are more complex than those found in the usual neutron or coupled-neutron gamma-ray problem, they yield a consistent approach for the calculation of local energy deposition.

Energy Technology Data Exchange (ETDEWEB)

DOE/NNSA and IRSN collaborated on a study of gamma-ray instruments and analysis methods used to perform isotopic measurements of special nuclear materials. The two agencies agreed to collaborate on the project in response to inconsistencies that were found in the various versions of software and hardware used to determine the isotopic abundances of uranium and plutonium. IRSN used software developed internally to test the MGA and FRAM isotopic analysis codes for criteria used to stop data acquisition. The stop-criterion test revealed several unusual behaviors in both the MGA and FRAM software codes.

CERN Document Server

AMS is a particle detector designed to perform high precision measurements of the cosmic rays fluxes with the main goals of searching for anti-nuclei, as remnants of primordial anti-matter, and of measuring the faintest components of the cosmic flux, anti- protons, positrons and high energy photons. To fulfill the requirements of large acceptance, long exposure time and excellent particle identification needed to achieve the intended results, AMS will operate in space as an attached payload to the International Space Station (ISS), being the first full featured particle physics experiment to operate in the Earth orbit. The AMS-02 accurate measurements of cosmic-ray nuclei, protons, antiprotons, electrons and positrons will be completed by high energy gamma rays detection. The experiment will detect gamma-rays, either by reconstructing e+e? pairs generated by photons converted ...

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Plantago ovata Forsk - an economically important medicinal plant - was analyzed for trace elements and chlorophyll in a study of the effects of gamma radiation on physiological responses of the seedlings. Proton-induced X-ray emission (PIXE) technique was used to quantify trace elements in unirradiated and gamma-irradiated plants at the seedling stage. The experiments revealed radiation-induced changes in the trace element and chlorophyll concentrations.

International Nuclear Information System (INIS)

Evaluated spectroscopic data for all nuclei with mass number A = 216 are presented together with the relevant level schemes from radioactive decay and nuclear reaction studies. The experimental data are evaluated, inconsistencies and discrepancies are noted, and adopted values for level and #gamma#-ray energies, #gamma# intensities, as well as for other nuclear properties are given. The present evaluation supersedes the earlier one on A = 216 by A. Artna-Cohen (1997Ar04), published in Nuclear Data Sheets 80, 157 (1997).

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Natural radioactive materials were used for detector calibration. We found that KCl is a very suitable material for this purpose. The efficiency curve shape was derived by using {gamma} ray lines of {sup 214}Bi normalised using a known quantity of KCl in the same geometry. The best fit was found by the least squares method. The summing correction coefficients for {sup 214}Bi are determined. (orig.).

Energy Technology Data Exchange (ETDEWEB)

The future e{sup +}e{sup -} linear colliders can also operate in the e{gamma} or {gamma}{gamma} modes. In the context of the top-color assisted technicolor (TC2) model, we study the single charged top-pion production process {gamma}{gamma} {yields} tb-bar{pi}{sub t}{sup -}. The results show that the production rates can reach the level of tens fb with reasonable parameter values. So one can expect that enough signals could be produced in future high-energy linear collider experiments. Furthermore, the flavor-changing (FC) decay mode {pi}{sub t}{sup -} {yields} bc-bar is the best channel to detect the charged top pion due to the clean standard model background. With a large number of events and the clean background, the charged top pion should be observable at future linear colliders operating in {gamma}{gamma} mode at the TeV energy scale.

International Nuclear Information System (INIS)

The O(#alpha#) electroweak radiative corrections to #gamma##gamma##->#WW#->#4f within the electroweak standard model are calculated in double-pole approximation (DPA). Virtual corrections are treated in DPA, leading to a classification into factorizable and non-factorizable contributions, and real-photonic corrections are based on complete lowest-order matrix elements for #gamma##gamma##->#4f+#gamma#. Soft and collinear singularities appearing in the virtual and real corrections are combined alternatively in two different ways, namely by using the dipole subtraction method or by applying phase-space slicing. The radiative corrections are implemented in a Monte Carlo generator called Coffer #gamma##gamma# - the computer code can be obtained from the authors upon request - which optionally includes anomalous triple and quartic gauge-boson couplings in addition and performs a convolution over ...

UK PubMed Central (United Kingdom)

The design of the time-resolved x-ray diffraction experiments reported in this and an accompanying paper was based on direct measurements of enzyme phosphorylation using [gamma-32P]ATP that were employed...Full Text Available

International Nuclear Information System (INIS)

Ferrite of system, namely Ni_1_-_xZn_xFe_2O_4 with x = (0.0, 0.2, 0.4, 0.6, 0.8, 1.0), have been prepared by solid state reaction to investigate the effect of gamma rays irradiations using Co"6"0 source on the cation distribution, structural and magnetic properties. The unirradiated and irradiated samples were then subjected to characterization techniques such as X-ray diffraction, magnetization and AC susceptibility. The results of these characterizations are found to be different for irradiated from that of the pristine sample. The modifications in respect of irradiated samples are explained in terms of the ion-induced disorder. The important result of #gamma#-irradiation on the cation distribution, structural and magnetic properties is the change of ratio Fe"2"+/Fe"3"+. Possible reasons on the results are proposed.

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Strong-interaction effects have been observed in the x-ray spectra of atoms formed with [Sigma][sup [minus

CERN Document Server

We aim to obtain a consistent description of non-thermal emissions from Abell 2256 and to give a prediction for a gamma-ray emission from this galaxy cluster. Assuming that a radio relic illuminates a localization of an ongoing merger, and that both radio and non-thermal part of hard X-ray emission are due to electron component of cosmic rays filling the relic, we derived from radio and hard X-ray properties of the relic in A2256 the magnetic field strength and number densities for relativistic electrons and protons. Due to the interpretation of the radio relic as a structure formed just where a shock front is, we discuss a gamma-ray emission at the cluster periphery. The estimated strength of the magnetic field in the relic is equal to 0.05 \\muG, while the amplitude of the electron number density varies from 3 x 10^{-4} to 3 x 10^{-5} cm^{-3} (respectively for the relic thickness ...

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In this paper we present status and developments of the Duke storage ring facility. The Duke storage ring facility provides the unique combination of phase-locked light sources ranging from high power OK-4 XUV FEL to quasimonochromatic {gamma}-ray beam and IR/X-ray spontaneous radiation. The XUV OK-4 FEL, which is collaborative project with BlNP, Novosibirsk, is in operation since November, 1996. The OK-4 UV FEL is also used for production of nearly monochromatic {gamma}-ray s with tunable energy. We present the results of UV lasing with the OK4 FEL and selected results of its applications. We will discuss our future plans for extension of this source and status of the construction of dedicated used facility adjacent to the FEL building. (author)

Energy Technology Data Exchange (ETDEWEB)

We studied the effects of small, <20 {micro}m, Te inclusions on the energy resolution of CdZnTe gamma-ray detectors using a highly collimated X-ray beam and gamma-rays, and modeled them via a simplified geometrical approach. Previous reports demonstrated that Te inclusions of about a few microns in diameter degraded the charge-transport properties and uniformity of CdZnTe detectors. The goal of this work was to understand the extent to which randomly distributed Te-rich inclusions affect the energy resolution of CZT detectors, and to define new steps to overcome their deleterious effects. We used a phenomenological model, which depends on several adjustable parameters, to reproduce the experimentally measured effects of inclusions on energy resolution. We also were able to hound the materials-related problem and predict the enhancement in performance expected by reducing the size and number of Te inclusions within ...

International Nuclear Information System (INIS)

A calculation method of the X-ray radiation dose (energy of gamma- radiation remains in the range of energies where the mechanism of photoelectric absorption is the prevailing one) absorbed in the absorbers of final thickness is suggested. Calculations of resorption of secondary radiation (characteristic fluorescences) in the substance and kinetic energy of photoelectrons caused by this resorption (it would be enough to consider one or two hard series) are presented. Calculation of the spectrum of photoelectron energy yield in TeInSe_2 monocrystal for 0.1-0.5 A range of X-ray radiation is conducted by the developed methods.

International Nuclear Information System (INIS)

The effect of resonance, observed in X-ray waveguide layered structures in a characteristic way influences the scattering properties of the films. It is well known that the resonant region in the reflectivity shows a series of minima, usually very deep and extremely narrow. The positions and depths of the minima depend only on X-ray waveguide and quasi X-ray waveguide film structural properties, on the X-ray wavelength and on the incident beam divergence. In the present work we propose and discuss the application of the X-ray waveguide and quasi X-ray waveguide film structures as a tools to experimental evaluation of some quantities related to X-ray reflectometric and diffractometric measurements, like the beam divergence, wavelength, or angular distance. Examples of application of X-ray waveguide as ...

CERN Document Server

Aims: To provide a significantly improved probability distribution for the H-test for periodicity in X-ray and $\\gamma$-ray arrival times, which is already extensively used by the $\\gamma$-ray pulsar community. Also, to obtain an analytical probability distribution for stacked test statistics in the case of a search for pulsed emission from an ensemble of pulsars where the significance per pulsar is relatively low, making individual detections insignificant on their own. This information is timely given the recent rapid discovery of new pulsars with the Fermi-LAT t $\\gamma$-ray telescope. Methods: Approximately $10^{14}$ realisations of the H-statistic ($H$) for random (white) noise is calculated from a random number generator for which the repitition cycle is $\\gg 10^{14}$. From these numbers the probability distribution $P(>H)$ is calculated. Results: The distribution of $H$ is is found to be ...

Energy Technology Data Exchange (ETDEWEB)

The NIS-6 group at Los Alamos National Laboratory pioneered the development of Tomographic Gamma Scanning and continue to improve its utility in real measurement situations. Building on this experience we report the development of a state of the art TGS system suitable for industrial applications. The image reconstruction and visualization software has been integrated into the familiar Canberra NDA2000 software suite which also handles all other aspects of the data acquisition and management. In this paper we describe the salient design and performance parameters of the system. The application of gamma-ray tomography to safeguards for improved assay accuracy and knowledge confirmation is discussed. In particular we compare and contrast the relative merits of this TGS and a traditional Segmented Gamma Scanner and illustrate how the 3-D visualization of the TGS image can provide valuable additional information.

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Short communication.

International Nuclear Information System (INIS)

Short communication.

International Nuclear Information System (INIS)

Active galactic nuclei (AGNs) and quasars (QSOs) appear to emit roughly equal energy per decade from radio to gamma-ray energies (e.g. Ramaty and Ligenfelter 1982). This argues strongly for a nonthermal radiation mechanism (see Rees 1984). In addition, statistical studies have indicated that the spectra of these objects in the IR-UV and 2 to 50 keV x-ray band, can be fitted very well with power laws of specific indices. These spectral indices do not seem to depend on the luminosity or morphology of the objects (Rothschild et al. 1983; Malkan 1984), and any theory should account for them in a basic and model independent way. If shocks accelerate relativistic protons via the first-order Fermi mechanism (e.g. Axfor 1981), the radiating electrons can be produced as secondaries throughout the source by proton-proton (p-p) collisions and pion decay, thus eliminating Compton losses (Protheroe and Kazanas 1983). As shown by Kazanas (1984), if ...

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The relative merits and difficulties of the primary and secondary origin hypotheses for the observed cosmic ray antiprotons, including the low energy measurement of Buffington, were examined. It is concluded that the cosmic ray antiproton data may be strong evidence for antimatter galaxies and baryon symmetric cosmology. The present antiproton data are consistent with a primary extragalactic component having antiproton/proton approximately equal to .0032 + or - 0.7.

International Nuclear Information System (INIS)

The devised radionuclide analyzer for the determination of total sulfur in coal includes two radionuclide sources with different energies, which are accommodated in collimators fitted with adjustable diaphramgs. The sample compartment is located between the two sources. Moreover, an X-ray fluorescence standard can be slid into the sample compartment. A proportional detector for X-ray fluorescence and scattered gamma radiation is located off the sample compartment. The input of the proportional detector is interfaced to the output of a high-voltage supply, the output, to the information input of a control-and-evaluation unit. One of the control outputs of the control-and-evaluation unit is connected to the input of the sliding mechanism for the X-ray fluorescence standard. This arrangement enables automatic energy calibration of the analyzer. The analyzer can measure not only total sulfur in coal by ...

Energy Technology Data Exchange (ETDEWEB)

A model for generating the observed cosmic-ray antiproton spectrum in plasma consisting mainly of electron--positron pairs (n/sub plus-or-minus//n/sub p/> or approx. =10) is discussed. Coulomb collisions in the plasma would cause additional energy losses, significantly enhancing the antiproton flux at energies < or approx. =1 GeV. The computed p-bar/p ratio satisfactorily fits the observations.

Energy Technology Data Exchange (ETDEWEB)

At the RIKEN-RAL Muon Facility, {mu}{sup -} to {alpha} sticking K{sub {beta}} X-rays were observed for the first time taking advantage of the pulsed beam structure. The precision of the present measurements was insufficient to distinguish between theoretical models, however the observed K{sub {beta}}/K{sub {alpha}} X-ray intensity ratio tends to be smaller than most of these theoretical predictions.

CERN Document Server

We present the X-ray properties of a sample of 17 radio sources observed with the Chandra X-ray Observatory as part of a project aimed at studying the X-ray emission from their radio jets. In this paper, we concentrate on the X-ray properties of the unresolved cores. The sample includes 16 quasars (11 core-dominated and 5 lobe-dominated) in the redshift range z=0.30--1.96, and one low-power radio-galaxy at z=0.064. No diffuse X-ray emission is present around the cores of the quasars, except for the nearby low-power galaxy that has diffuse emission on a scale and with a luminosity consistent with other FRIs. No high-amplitude, short-term variability is detected within the relatively short Chandra exposures. However, 1510-089 shows low-amplitude flux changes with a timescale of $\\sim$25 minutes. The X-ray spectra of the quasar cores are ...

Energy Technology Data Exchange (ETDEWEB)

We irradiated proton beams on the ears of rabbits and the Harding-Passey mouse melanoma and observed their morphological change. We used 52 MeV proton beams from the INS-FM cyclotron. We adjusted the energy of the proton beams to be at the plateau part of the Bragg curve, at the half-way point of the Bragg peak, and at the Bragg peak. The amount of radiation was 5000rad in each case. The Harding-Passey mouse melanoma was transplanted into the subcutan of a three week old mouse. In this experiment, we used tumors, the diameter of which grew up to 1.5-2cm in 2-3 weeks after the transplantation. Using the jroscope, we observed both lightly and severely damaged cells. Using proton irradiation with the Bragg peak located at depth of 1mm in the rabbit's ears, we studied the change in the tissue. Irradiated epidermis fell off and was eroded because of radiation damage, but the rear surface of the rabbit's ears was only slightly ...

International Nuclear Information System (INIS)

A large matrix of simple alloys and complex commercial type steels was irradiated over a range of fluxes at 60 FC up to a fast fluence of about 3 x 10"2"2 n/m"2. Combined with data in the literature, these results show a negligible effect of flux on irradiation hardening in the range of 2 x 10"1"3 to 5 x 10"1"8 n/m"2-s. This observation lends indirect support to the proposal that the accelerated embrittlement in the High Flux Isotope Reactor surveillance steels was due to an anomalously high level of damage from gamma rays. A weak dependence of hardening on a number of elements, including copper, nickel, phosphorus, molybdenum and manganese, can be described by a simple empirical chemistry factor. Particular combinations of elements resulted in hardening differences of up to about 60% in the complex commercial type steels and up to about 100% in simple model alloys. Direct effects of microstructure appear to be minimal. ...

International Nuclear Information System (INIS)

The L-shell x-ray intensity ratios I(L_#beta#)/I(L_#alpha#) and I(L_#gamma#)/I(L_a_l_p_h_a) for elements with 73 #<=# Z #<=# 83 have been measured at photon incident energies of 17.8, 25.8 and 46.9 keV. The emitted x-rays were measured with a Si(Li) detector system. The results for Re, Pt and Tl are being reported for the first time. A comparison is made of the experimental results with the calculated values obtained by using the theoretical x-ray emission rates, subshell ionisation cross sections, subshell fluorescence yields and Coster-Kronig transition probabilities. The experimental results are in reasonable agreement with the theoretical values. (author).

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We investigate the possibility of observing strong interactions of longitudinally polarized weak vector bosons in the process {gamma}{gamma}{yields}ZZ at a photon linear collider. We make use of polarization of the photon beams and cuts on the decay products of the Z bosons to enhance the signal relative to the background of transversely polarized ZZ pairs. We find that the background overwhelms the signal unless there are strong resonant effects, as for instance from a technicolor analogue of the hadronic f{sub 2}(1270) meson. ((orig.)).

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Wood/polymer composites (WPC) have been prepared from pinewood with different compounds using gamma irradiation: butyl acrylate, butyl methacrylate, styrene, acrylamide, acrylonitrile, and unsaturated polyester styrene resin. The polymer loading was determined with respect to the compound concentration and the irradiation dose. The polymer loading increases generally with increase in the monomer or polymer concentration. Tensile and compression strength have been improved in the four cases, but no improvement was observed using unsaturated polyester styrene resin or acrylamide.

CERN Document Server

We report a study of $B\\to (J/\\psi \\gamma) K$ and $B\\to (\\psi' \\gamma)K$ decay modes using $772\\times 10^{6}$ $B\\bar{B}$ events collected at the \\Upsilon(4S)$ resonance with the Belle detector at the KEKB energy-asymmetric $e^+ e^-$ collider. We observe $X(3872) \\to J/\\psi \\gamma$ and report the first evidence for $\\chi_{c2} \\to J/\\psi \\gamma$ in $B\\to (X_{c\\bar{c}}\\gamma) K$ decays, while in a search for $X(3872) \\to \\psi' \\gamma$ no significant signal is found. We measure the branching fractions, $\\mathcal{B}(B^{\\pm} \\to X(3872) K^{\\pm}) \\mathcal{B}(X(3872) \\to J/\\psi\\gamma)$ $=$ $(1.78^{+0.48}_{-0.44}\\pm 0.12)\\times 10^{-6}$, $\\mathcal{B} (B^{\\pm} \\to\\chi_{c2} K^{\\pm})$$=$ $(1.11^{+0.36}_{-0.34} \\pm 0.09) \\times 10^{-5}$, $\\mathcal{B}(B^{\\pm} \\to X(3872) K^{\\pm}) ...

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A gamma-ray spectrometer (GRS) has been built and delivered to the Mercury MESSENGER spacecraft which launched on August 3, 2004, from Cape Canaveral, Florida. The GRS, a part of seven scientific instruments on board MESSENGER, is based on a coaxial high-purity germanium detector. Gamma-ray detectors based on germanium have the advantage of providing excellent energy resolution, which is critical to achieving the science goals of the mission. However, germanium has the disadvantage that it must operate at cryogenic temperatures (typically {approx}80 K). This requirement is easy to satisfy in the laboratory but difficult near Mercury, which has an extremely hot thermal radiation environment. To cool the detector, a Stirling cycle mechanical cooler is employed. In addition, radiation and conduction techniques a are used to reduce the GRS heat load. Before delivering the flight sensor, a complete thermal prototype was built and tested. The results ...

International Nuclear Information System (INIS)

In conducting aircraft surveys for uranium, it is found that temperature inversions can give spurious results because they promote accumulation of radon gas in the atmosphere. The "2"1"4Bi (daughter product of radon) gamma-rays detected from the atmosphere-borne radon are difficult to separate from the "2"1"4Bi gamma-rays originating from the ground, and providing a signature for uranium deposits. The purpose of the present study was to examine the feasibility of making remote temperature soundings of the atmosphere below a low-flying aircraft (140 m or less above ground) by the inversion of radiance measurements taken in the 15-micron carbon dioxide absorption band. Such measurements would identify those temperature inversion conditions possibly leading to an unacceptably large background of gamma-rays from the atmospheric radon. Thus, the incidence of spurious aerial survey data could be greatly reduced. An atmospheric ...

International Nuclear Information System (INIS)

Magnetically driven non-stationary acceleration of jets in active galactic nuclei results in the leading parts of the flow being accelerated to much higher Lorentz factors than in the case of steady-state acceleration with the same parameters. The higher Doppler-boosted parts of the flow may dominate the high-energy emission of blazar jets. We suggest that highly variable GeV and TeV emission in blazars is produced by the faster moving leading edges of highly magnetized non-stationary ejection blobs, while the radio data trace the slower-moving bulk flow. Thus, the radio and gamma-ray emission regions have different, but correlated, Doppler factors. High-energy emission is generated, typically within the optically thick core, in the outer parts of the broad-line emission region, avoiding the radiative drag on the faster parts of the flow. The radio emission should correlate with the gamma-ray emission, delayed with frequency-dependent time lag ...

CERN Document Server

We investigate monoenergetic gamma-ray signatures of Z^1 dark matter annihilations in a non-minimal Universal Extra Dimensions model. The self-interactions of the non-Abelian Z^1 gauge boson give rise to a large number of contributing Feynman diagrams that do not exist for annihilations of the Abelian gauge boson B^1, which is the standard Kaluza-Klein dark matter candidate. We find that the annihilation rate is indeed considerably larger for the Z^1 than for the B^1. Even though relic density calculations indicate that the mass of the Z^1 should be larger than the mass of the B^1, the predicted fluxes are of the same order of magnitude. We compare our results to existing experimental limits, as well as to future sensitivities, for image air Cherenkov telescopes, and we find that the limits are reached already with a moderately large boost factor. However, the realistic prospects for detection depend on the energy resolution, as well as on the continuous ...

Energy Technology Data Exchange (ETDEWEB)

The thermal neutron column of the JRR-2 reactor was remodelled in order to install a medical irradiation facility. The design experience and the cource of this remodelling are presented. At first, the thermal neutron flux was lower than expected, and the expected radiation condition was achieved by the following improvements: (1) removal of graphite from the thermal neutron column to increase the neutron flux, (2) twice increase of bismuth shielding and the shift of its position to improve the shielding effect against gamma ray, (3) application of B{sub 4}C rubber on the both surfaces of the shielding door to suppress the secondary gamma ray generation from the structural materials, (4) LiF tiles are applied on the inner face of the neutron beam exit hole to suppress the secondary gamma ray from the beam exit, and (5) installment a cone-shape polyethylene ...

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A single-crystal x-ray study under pressure reveals a phase transition from an in-plane 2x2 commensurate potassium superstructure to a new ..sqrt..3x..sqrt..3 commensurate superstructure. This is the first such transition to be observed; it is related to the recently discovered staging transition of KC/sub 8/ under pressure. In addition this staging transition was observed to occur more slowly and at much lower pressures than in the reported neutron-scattering experiment on highly oriented pyrolytic graphite samples. 13 references, 2 figures.

Energy Technology Data Exchange (ETDEWEB)

Cosmic rays at ground level have been collected using the NMSU/Wizard - MASS2 instrument. The 17-hr observation run was made on September 9. 1991 in Fort Sumner, New Mexico, Usa. Fort Sumner is located at 1270 meters a.s.l., corresponding to an atmospheric depth of about 887 g/cm{sup 2}. The geomagnetic cutoff is 4.5 GV/c. The charge ratio of positive and negative muons and the proton to muon ratio have been determined. These observations will also be compared with data collected at a higher latitude using the same basic apparatus.