132Cs gamma radiation

The decay of¹³²Cs was studied by means of Ge(Li) detectors and a magnetic beta-ray spectrometer. The energies and intensities of the transitions in¹³²Xe and¹³²Ba were determined. Of the decay schemes proposed hitherto, that of Johnson et al. [Phys. Rev.138 (1965), B 520] was confirmed.     

Cherenkov-transition radiation in gamma frequency region

The spectral and angular distributions, as well as the total number of photons of gammaray Cherenkov-transition radiation (GCTR) produced by charged particles in the photon energy region (0.8–2) MeV, are calculated using the results of the recent discovery that in the above-mentioned region the refraction index of some materials is greater than unity, n(ω) > 1, due to Delbruck scattering on Coulomb field of nuclei. Using the results of the numerical calculations carried out, we propose an experimental arrangement for observation and study of GCTR produced by electrons with energy much higher than the threshold energy of GCTR (～10 GeV). Some applications of GCTR, in particular, the search for new materials with n(ω) > 1 in gamma region with the help of this method, are discussed.     

Correlated gamma rays in synchrotron radiation

A new intensity correlation phenomenon at gamma-ray wavelengths is described. The influence of detector size on correlation effects is analyzed quantitatively. It is shown that dedicated synchrotron radiation sources, such as the Mössbauer beam line at the ESRF, will have characteristics allowing experimental observations of the correlation phenomenon.     

The radiation shielding offered by the commercial glass installed in Bangladeshi dwellings

One sign of a vibrant Bangladeshi economy has been the move away from the use of more traditional housing materials towards a preference for modern constructional media. Glass, one such example, used both decoratively and in a structural context, offers various advantageous properties and facets including a protective feature against radiation that has not previously been considered. Current interest examines the dosimetric possibilities offered by the commercial glass as a secondary shield and also in retrospective ionising radiation exposure analysis. Four popular brands of window glass are investigated, all available within the local market (PHP-Bangladesh, Usmania-Bangladesh, Nasir-Bangladesh and Rider-China), all with the same thickness and colour, varying in terms of elemental weight fractions as evaluated by energy dispersive X-ray analysis. As potential attenuators of transmitted radiation thereby forming secondary barriers against radiation exposure from penetrating radiations, the four brands of glass have been studied using photon energies from 59 up to 1332 keV, a range of values representative of that potentially encountered in incidents. Use has been made of a well-shielded high-purity germanium γ-ray spectrometer and associated electronics, providing for evaluation of the characteristic barrier parameters of half-value layer, radiation protection efficiency and effective atomic number (Z_eff). Of the four brands investigated, Rider provides superior secondary shielding performance. Concerning potential retrospective dosimetry the effective atomic number of the glass samples are comparable with that of the commercial thermoluminescence (TL) dosimeter TLD-200. At high doses, the TL yields are sufficient to provide for retrospective accident dosimetry.     

On the connection between gamma radiation and radio radiation in pulsars

A model proposed for radio radiation from a pulsar suggests that coherent radio radiation is generated in a vacuum gap over the polar cap of a neutron star. In this model, x and gamma rays from the pulsar are generated due to the inverse Compton scattering of radio radiation by ultrarelativistic electrons accelerated in the gap.     

Environmental gamma and radon dosimetry in Venezuela

Environmental gamma exposure and radon concentration levels measured in Venezuelan regions are presented. A new generation image analyser was used for particle track counting in CR-39 detectors. Mineral water wells from where water is supplied for massive consumption have an alpha activity around 0.450 Bq L⁻¹ and few of them have concentrations above 50 Bq L⁻¹. Coastal potable water activity is on the average around 5.3 ± 12% Bq L⁻¹. Indoor radon national average is 36 ± 5% Bq m⁻³; in two of the 36 monitored sites, the measured average is above 400 ± 5% Bq m⁻³. In air gamma dose values are between 100 and 144 nGy h⁻¹. In soil, ¹³⁷Cs concentration is around 0.5 and 10 Bq kg⁻¹ at the depth of down to 20 cm. Building materials were included in this study. ⁷Be and ¹³⁷Cs were measured in low concentration in tropical plants on Tepuy-s (sacred mountains in the Amazonas State). Geological active faults were identified by radon concentration measurements using LR-115.     

Two-quantum stimulated emission of gamma radiation

Various schemes exploiting two-quantum nuclear transitions for the generation of coherent gamma radiation (stimulated anti-Stokes and stimulated two-quantum de-excitation of isomeric nuclei in an active medium with the hidden population inversion of nuclear states and the ignition of an avalanche-like stimulated gamma-emission by counterpropagating X-rays) are discussed.     

Temporal optics of recoil-free gamma radiation

A discussion is given of the time-behavior of recoil-free γ-radiation passing through a resonant medium. The classical dispersion theory of Hamermesh is extended to account for different linewidths in source or absorber so that a synchrotron-radiation source can be simulated. A result, essentially the same as that of Kagan et al., follows in the limit of large source width. A review is given of the quantum beats which result from the absorption of one line of a frequency-modulation spectrum. An example is given of the measurement of second-order Doppler shift in Fe−Be by the method of quantum beats. Finally, there is a discussion of the measurement by quantum beats of the very small energy shift in a⁵⁷Co−Cu source by a magnetic field.     

Quantum optics with nuclear gamma radiation

Some features of quantum optics related to inversionless amplification are translated to nuclear systems. Nuclei and nuclear transitions differ in several ways from atomic systems: gamma radiation has a much shorter wavelength (of the order of lattice-distances), nuclear transitions are many orders of magnitude weaker than atomic ones (making nuclear pumping extremely hard), no coherent gamma-ray sources are available to produce bichromatic gamma radiation. All this makes it very hard to merely translate quantum optical results to nuclear systems. We show that under very specific conditions destructive quantum interferences can occur in the nuclear absorption probability, while the stimulated emission probability is not affected. Nuclear level mixing plays a crucial role in this. This revised version was published online in August 2006 with corrections to the Cover Date.     

Application of commercial glass in gamma radiation processing

A commercial glass has been investigated using UV–Vis spectrophotometry to study the gamma radiation response of this material and to evaluate its dosimetric characteristics: dose response, room temperature fading, effect of relative humidity during post-irradiation storage, temperature during irradiation and the dose rate effect. The overall uncertainty was also estimated.The obtained results demonstrate that the influence quantities on the glass response might be very significant and suitable corrections are indispensable.     

Noise sensitivity to gamma radiation in Si-jfet devices

The result of noise measurements for a Charge Sensitive Preamplifier based on Si-Field Effect Transistor exposed to a total Gamma ray dose of 30 v Mrad have been reported. The radiation effect on the DC parameters of single transistors was also tested. Our study has shown that, there are no changes on the DC parameters. Meanwhile the noise level, which was evaluated by the total equivalent noise charge, was clearly increased. The results of noise measurements were analyzed and compared with theoretical predictions. The temperature and time-dependent effects on the noise had also been reported after irradiation. All measurements were performed for biased and unbiased irradiated transistors.     

Determination of activity of <Superscript>51</Superscript>Cr on gamma radiation measurements

A method of determining the activity of intensive distributed -sources on the measurement of the continuous spectrum of radiation, for example the internal bremsstrahlung, is developed. The recurrent formula for reconstructing of a continuous spectrum, registered in a Ge detector, at distorting it in the detector. The method of precise measurements of the spectrum of ⁵¹Cr internal bremsstrahlung using two point sources of low activity is described.     

Picosecond X-ray plasma radiation measurements

Direct picosecond measurements of X-ray laser plasma radiation were performed with a high-speed X-ray image-converter camera (ICC). This camera operates in the single-frame mode with an exposure time ranging from 5 ns to 0.5 μs and in the streak mode with 5 × 10⁹ to 5 × 10⁷ cm/s streak velocities. Its temporal resolution in the streak mode was calculated to be about 7 ps. A plasma was created by focussing 10 ps 1 to 2 joule laser pulses onto a titanium target placed in a vacuum chamber. The halfwidth of the recorded X-ray pulses varied from 30 to 60 ps.     

Level mixing induced transparency for gamma radiation

The propagation of gamma radiation through a resonant medium in the case of interfering quantum transition paths is considered. The interference is made possible by a field that mixes the crossing spin levels in the excited nuclear state and splits two degenerate transitions into two V-type transitions. If forward resonant scattering allows for a change of the gamma radiation polarization, then the two V-transitions are coupled, which results in destructive interference. In this case the absorption is reduced in a particular frequency domain. PACS 42.50.Gy; 33.45.+x     

In-flight radiation measurements on STS-60

A joint investigation between the United States and Russia to study the radiation environment inside the Space Shuttle flight STS-60 was carried out as part of the Shuttle-Mir Science Program (Phase 1). This is the first direct comparison of a number of different dosimetric measurement techniques between the two countries. STS-60 was launched on 3 February 1994 in a nearly circular 57 degrees x 353 km orbit with five U.S. astronauts and one Russian cosmonaut for 8.3 days. A variety of instruments provided crew radiation exposure, absorbed doses at fixed locations, neutron fluence and dose equivalent, linear energy transfer (LET) spectra of trapped and galactic cosmic radiation, and energy spectra and angular distribution of trapped protons. In general, there is good agreement between the U.S. and Russian measurements. The AP8 Min trapped proton model predicts an average of 1.8 times the measured absorbed dose. The average quality factor determined from measured lineal energy, y, spectra using a tissue equivalent proportional counter (TEPC), is in good agreement with that derived from the high temperature peak in the 6LiF thermoluminescent detectors (TLDs). The radiation exposure in the mid-deck locker from neutrons below 1 MeV was 2.53 +/- 1.33 microSv/day. The absorbed dose rates measured using a tissue equivalent proportional counter, were 171.1 +/- 0.4 and 127.4 +/- 0.4 microGy/day for trapped particles and galactic cosmic rays, respectively. The combined dose rate of 298.5 +/- 0.82 microGy/day is about a factor of 1.4 higher than that measured using TLDs. The westward longitude drift of the South Atlantic Anomaly (SAA) is estimated to be 0.22 +/- 0.02 degrees/y. We evaluated the effects of spacecraft attitudes on TEPC dose rates due to the highly anisotropic low-earth orbit proton environment. Changes in spacecraft attitude resulted in dose-rate variations by factors of up to 2 at the location of the TEPC.     

Hard gamma radiation in the decay of Lu176m

Gamma lines 1·05 MeV(4 × 10^–6 quanta/decay) and 1·14 MeV (9 × 10^–6 quanta/decay), giving evidence of the existence of a new level in Hf¹⁷⁶ with an energy of 1·14 MeV, were found in the decay of Lu^176m with a half-life of 3·7 hours, using the scintillation method. The component of the beta spectrum, exciting this level, has a maximum energy of 0·17 MeV and logft=8·3. The spin of this level proved to be equal to one. The level was interpreted as a single-particle neutron level withn ₀: 5/2^– (512),n ₁: 7/2^– (514);I=1⁺.

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- Lu^176m

Lu^176m 3,7 - 1,05 MeV (4.10^–6 /) 1,14 MeV (9.10^–6 / /), Hf¹⁷⁶ 1,14 MeV. -, , 0,17 MeV logft = =8,3. . cn ₀: 5/2^– (512),n ₁: 7/2^– (514);I = 1⁺h

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The authors thank L. K. Peker from the Leningrad State University for a helpful discussion of their results.