Table of contents

From collective model sum rules derived from the various possible intermediate couplings of a zero coupled product of four E2 operators, approximate expressions are obtained for the reduced transition probability B(E2,4⁺ to 2⁺) and the magnitude of the static quadrupole moment mod Q₂₊ mod of the first 2⁺ state for an even-even nucleus in terms of other E2 transition strengths.

Results of calculations are given for the moderation of 14 MeV neutrons produced by the fusion reaction is in compressed D-T sphere, radius 6*10^-4cm, density 2*10³ g cm^-3. It is shown that, in addition to the 3.5 MeV energy available to the pellet from the alpha particle, 0.9 MeV is deposited by the neutrons.

Current data on pi N backward scattering at 6 GeV/c are analysed, assuming I_u=¹/₂ is dominated by an N_alpha Regge pole. Two solutions are found, one resembling previous results, the other differing in the sign of ReH₊₊^3/2. The first solution can have a 'geometrical' structure of zeros in I_u=³/₂, the second (which is a better fit) has zeros near u=0 in both ImH₊₊^3/2 and ImH_+-^3/2. The solutions can be distinguished by measuring the sign of backward charge exchange polarization.

The spectra shapes of the external bremsstrahlung produced by ³²P and ³⁵S beta rays when they are completely absorbed in different elements such as carbon, aluminium, copper, silver, tin and lead are experimentally measured with a multichannel NaI(Tl) scintillation spectrometer along with a standard geometrical arrangement. After making all the necessary corrections, the final distributions are compared with the modified Bethe-Heitler theory. The experimental results are in excess over theory for high Z elements and this experimental excess over theory is found to increase with increasing nuclear mass and photon energy.

The odd-A Te isotopes ¹²³Te, ¹²⁵Te, and ¹²⁷Te are studied in a version of the unified vibrational model which incorporates both pairing effects and anharmonicity in the core vibrations. The neutron quasiparticle states in the N=50-82 shell are coupled to anharmonic vibrations of the corresponding even cores. The calculated results are discussed in the light of the recent experimental findings.

For pt.IV see ibid., vol.I, p.213, 1975. Untruncated shell-model calculations have been performed for even-parity low lying levels in ²³Na, ²³Mg and ²³Ne, using the two-body interactions of Kuo and Preedom and Wildenthal. Excitation energies, transition rates and static moments have been calculated. When allowance is made for shifted bands in all spectra good agreement is achieved with both interactions for a wide range of data. The structure of the three nuclei is discussed in the light of these calculations.

The 4.350 MeV(3⁺) and 5.716 MeV(4⁺) states in ²⁶Mg have been studied with particle gamma ray angular correlation measurements using the reactions ²⁶Mg( alpha alpha ' gamma ) ²⁶Mg with Ge(Li) detectors. Branching ratios and E2/M1 mixing ratios were deduced; in particular a new 815 keV transition (5.716 to 4.901 MeV) has been found. The E2 transition strengths of the cascading gamma rays with 1366 keV (4⁺ to 3⁺) and 1412 keV (3⁺ to 2⁺) of 3+or-1 and 9_-3⁺⁴ Weisskopf units respectively support the assignment of the 4.350 and 5.716 MeV states to the K^pi =2⁺ rotational band based on the 2.938 MeV (2⁺) states. The results are compared with recent deformed shell model calculations. Nineteen further states between 6 and 9.1 MeV were excited; a decay scheme has been established and several branching ratios are reported. The possible assignment of high spins to some of the higher states is discussed.

The ⁵⁶Fe(³He,⁴He) reaction has been measured at 83 MeV together with the elastic scattering for the ³He at 83 MeV and ⁴He at 86 MeV. The ³He scattering produced a unique optical potential when analysed with a six parameter model but contrasts with the analysis of the ⁴He scattering for which two acceptable optical potentials were found. The energy dependence of the ³He optical model potential cannot be accommodation over a wide range by a fixed geometry analysis. The limitations of DWBA under angular momentum mismatch conditions for the (³He,⁴He) reaction are discussed.

Measured differential cross sections for elastic and inelastic scattering of 104 MeV alpha -particles from ⁵⁶Fe are analyzed in terms of coupled channels on the basis of symmetric and asymmetric rotator models. The analyses use a semi-microscopic folding procedure and in some cases the conventional extended optical model is also used. Deformation parameters, RMS radii, multipole moments of the nuclear matter distribution, and transition probabilities have been extracted.

Measurements have been made of the differential cross sections for ³He scattering from the samarium isotopes Sm 144, 148, 150, 152, 154 at 53.4 MeV. An optical model analysis has been performed to compare with similar analyses using proton and alpha beams at the same energy.

An apparatus consisting of a stack of six scintillation counters interleaved with lead target material has been operated in underground laboratories at depths below the top of the atmosphere of 72 and 460 hg cm^-2. The probability that a muon transferred secondary energy in the range 0.1 to 30 GeV was determined from the recorded data. At the shallower depth the dominant process was knock-on and at the greater depth direct pair production was more significant. By comparing the rates of electromagnetic interactions at the two depths it was possible to make an estimate of the contribution due to pair production which was relatively insensitive to systematic errors. For secondary energies in the range 0.1 to 5 GeV the results confirm the theoretical predictions for both knock-on and pair production to within about 15% in each case.