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By employing the invariant four-dimensional representation of the photon- electron interaction, obtained from lowest-order quantum electrodynamics, the Compton scattering kernel is easily found in any coondinate frame. This procedure provides a simple alternative to the usual Lorentz transformation of the scattering kernel (from electron rest frame to frame of interest) used in radiation-hydrodynamics computations and associated movingmedia problems in transpont theory. Furthermore, arbitrary distributions of electrons can be conveniently handled in this representation, and standard predictions for electrons initially at rest can be recovered easily. (1 figure) (auth)

Some popular belief about the implications of scaling in deep inelastic electron nucleon scattering is destroyed. We compute certain moments similar to the Cornwall-Norton sum rules but which give at all values of Q2 precisely the coefficient functions occurring in the Wilson expansion of the product of two electromagnetic currents. Data in the range 1 ⩽ Q2 ⩽ 10 GeV2 seem to favour large anomalous dimensions. If we insist on canonical dimensions we have to conclude that asymptotia has not yet set in in this Q2 range.

It is demonstrated that the quautum theory of gravity can be a zero- slope limit of the generalized Virasoro model where the Regge intercept is fixed at two. The quautum theory of gravity is taken to mean Gupta-Feynman's perturbation on the flat background. The correspondence for the graviton Compton scattering is demonstrated by direct calculations. (LBS)

For elastic scattering, relations between spin-effects (for example, the well-known asymmetry-polarization equality) follow from time-reversal invariance. We show that if certain amplitude combinations vanish, there are strikingly similar relations between spin-effects for elastic and also inelastic reactions. This vanishing of amplitude combinations (denoted M -purity) corresponds asymptotically to purely natural or purely unnatural parity in the crossed channel. The M -purity relations hold for spin-configurations much more general than do the corresponding time-reversal invariance relations. The experimental evidence for purely natural parity exchanges in high energy vector meson photoproduction from nucleons is shown to be good for all amplitudes involving nonzero meson helicity, but less conclusive for the zero helicity ones. Using time-reversal invariance and a vector meson-dominance argument, this implies no unnatural parity contributions in high energy Compton scattering from nucleons. Because of this empirical evidence for M -purity in these two processes, a detailed application to spin-effects in Compton scattering and in vector meson photoproduction is made. Some time-reversal invariance relations in Compton scattering resemble the corresponding M -purity relations though the applicability of the two is different, and there are examples where only one of the two exists. Out of our illustrations, the only M -purity relations which change in form due to the extra amplitudes present in the inelastic reaction are the M -purity analogue and extensions of the asymmetry-polarization equality (of Compton scattering) referring to the photon; the change is the appearance of the elements ϱ 00 of the vector meson density-matrix ϱ. Our other examples of M -purity relations do not change in form in going over from the elastic reaction (Compton scattering) to the inelastic reaction (vector meson photoproduction).

Evidence is obtained for e- gamma events coming from the e/sup +/e/sup - / yields e/sup +/e/sup -/ gamma reaction in a particular kinematics where the cross section is well explained by a Williams-Weizsacker-type calculation for a quasi-real photon Compton scattering. It is suggested that such a reaction can provide a good test of QED in the timelike region at higher energies. (LBS)

We have measured inelastic Compton scattering of 21-GeV bremsstrahlung photons on protons, for ${p}_{T}$ above 1 GeV/c. The yield of photons after subtracting ${\ensuremath{\pi}}^{0}$ and $\ensuremath{\eta}$ decay contributions appears to be nonhadronic and is greater than parton-model predictions for integer-charged partons. The constituent-interchange model provides a possible explanation.

Previous work (see ibid., vol.16, 577) has been continued to determine the practical capabilities of the system. A higher resolution Ge(Li) detector has been used to portray the scattering along the lines of passage of a 137Cs gamma -ray beam, and from these results it is possible to construct density cross-sections of the body. The limitations are shown to be due to (a) signal/noise arising from multiple scattering in the body and (b) resolution, which is governed by the finite beam width and finite aperture needed in front of the crystal. A suggested design of a twin-headed machine for clinical use is given.

The ratio of the elastic to the inelastic differential Compton cross section of aluminium has been measured, using 241Am 59·54 keV gamma rays at a scattering angle of 150°. The sample thickness was 7 mm. A Monte Carlo procedure was used to correct the data for the effect of multiple scattering. The resultant cross section ratio of elastic to inelastic scattering was compared with the prediction of the Waller-Hartree theory and good agreement was obtained after the multiple scattering correction had been made. The Compton profile, after applying this correction, was in agreement with a previous measurement on a thin sample, and with a calculation based on an electron-gas model including correlation.

Calculations of secondary Compton scattering spectra are presented for 60 keV photons scattered at 180°. The presence of secondary scattering modifies measured spectra in such a way that apparent high-momentum tails are added to the valence profiles, and the heights of the normalized profiles are reduced. The Compton profile of Be has been measured using 60 keV photons and a small sample from which secondary scattering is negligible. Comparison of the results to those of X-ray diffractometer measurements [1, 2] points out secondary scattering effects present in the latter. The valence profiles have high-momentum tails, and the profiles are asymmetric with higher values on the low-energy side of the profiles. These effects are probably present in many reported profiles of low atomic number samples. Es werden die Rechnungen fur sekundare Compton-Streuspektren fur bei 180° gestreute 60 keV-Photonen mitgeteilt. Die sekundare Streuung modifiziert die gemessenen Spektren in einer Weise, das die auftretenden Hochimpuls-Auslaufer zu den Valenzprofilen addiert und die Hohen der normierten Profile reduziert werden. Die Comptonprofile von Be wurden mit 60 keV-Photonen und einer kleinen Probe, bei der sekundare Streuung vernachlassigbar war, gemessen. Der Vergleich der Ergebnisse mit denen von Rontgenstrahlen-beugungsmessungen [1, 2] weist auf die Anwesenheit sekundarer Streuungseffekte im letzteren Fall hin. Die Valenzprofile besitzen Hochimpuls-Auslaufer und die Profile sind assymmetrisch mit hoheren Werten an der Niederenergieseite der Profile. Die Effekte existieren wahrscheinlich in vielen veroffentlichten Profilen von Proben mit niedriger Atomzahl.

The problem of calculating analytical expressions for the spectral distribution of multiple X-ray scattering is considered. Previous results for scattering from stationary electrons are extended to include scattering from moving electrons. The spectral distribution for double scattering in which one collision is elastic and one inelastic is also derived. The limitations of such an analytical approach are discussed with a view to indicating the probable direction of future work.

An S-matrix theory of the electromagnetic interaction without infrared divergences is proposed. With the help of it the effects of the soft (both real and virtual) photons are considered without perturbation theory approximations. The following results are obtained. (1) The terms of order k−1, ln fk, k0 and k ln2k are found in the bremsstrahlung matrix element where k is the radiated energy (they are expressed through the matrix element of the process without radiation). (2) It is shown, that if dispersion relations exist at nonzero photon mass, then they exist at zero mass also. (3) The first three terms of the series expansion in energy near the threshold are found for the Compton scattering matrix element at fixed momentum transfers. Relation of the obtained results to high-energy scattering and relativistic eikonal models is considered.

A general calculational model describing the effects of neutrons and gamma rays on self-powered prompt-responding coaxial in-core radiation detectors is presented. The model accounts for external g...

The spectra of germanium detectors may be calculated with very simplified assumptions about the interaction processes if the calculated spectra should be used as an aid for the analysis of unknown spectra. Therefore a simple Monte Carlo procedure is described to calculate the spectra of all nuclides, the energies and intensities of which are known. The limits of the procedure are pointed out.

analysis of new X-ray and optical data confirms that the X-ray luminosityL x of a cluster of galaxies is strongly dependent on its richness. The radio powerP 1445 of clusters at 1445 MHz is independent of richness, but is greater on the average for clusters with dominant cD galaxies than for those withou. The radio emission depends on the activity of one of the brightest galaxies; dominant cD galaxies are often responsible for radio emission, especially if they have double or multiple nuclei. For a given richness, high values ofL x andP 1445 sometimes occur together, but no strict correlation betweenL x andP 1445 exists. Possible tests of thermal-bremsstrahlung and inverse-Compton theories for the X-ray emission are mentioned.