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A uniquely identified example of the decay of7BeA is presented. The mere fact that this species can exist has important consequences relating to the multiplet structure of the mass number 7 hypernuclei. The average binding obtained from the present event together with that of ref. (4) isB Λ=(4.9±0.5)MeV.

The distributions in energy and angle of the neutrons emitted from the interaction of l4.l-Mev neutrons with zirconium have been obtained by using nuclear emulsion plates as detectors. The energy distribution of the low-energy nonelastic neutrons is Maxwellian. The angular distribution of the lowenergy nonelastic neutrons (0.5 to 4.0 Mev) is found to be isotropic; whereas, that of the high-energy nonelastic neutrons (4.0 to 12.0 Mev) is peaked in the forward direction. The significance of these results in terms of the statistical model of the nucleus is discussed. (auth)

The analysis of pi --mesonic decays is used to determine the binding energies of the LAMBDA hyperons in /sup LAMBDA /H/sup 3/, /sub LAMBDA /H/sup 4/ , /sub LAMBDA /He/sup 4/, /sub LAMBDA /He/sup 5/, /sub LAMBDA /He/sup 7/, / sub LAMBDA /Li/sup 7/, /sub lambda /Li/sup 8/, /sub LAMBDA /Li/sup 9/, /sub LAMBDA /Be/sup 8/, /sub LAMBDA /Be/sup 9/, B/sup 11/ , /sub LAMBDA /B/sup 12/, and /sub LAMBDA /C/sup 13/. (T.F.H.)

Further results are presented on the binding energies of hypernuclei of mass numberA>5. The data from 56 \gp{su\t-} of such hypernuclei are combined with the previously existing data. Problems in the identification of the heavier hypernuclei are critically discussed. The possible existence of an isomeric state of7HeΛ as suggested byPniewski andDanysz (2) is considered.

A technique for the measurement of neutron spectra which is independent of neutron direction has been studied. The technique consists of measuring all proton tracks in a known volume of type C2 Ilford emulsion, in which shrinkage has been reduced by treating the plates with rosin. By a suitable differentiation of the proton spectrum the absolute flux of neutrons as a function of energy is determined. Rotated plates were exposed to 0.8 and 1.3 Mev neutrons. 4000 tracks were measured, and two peaks with a width ∼150 kev at half‐maximum were obtained. The statistical accuracy of the neutron flux in the two peaks is about ten percent. The flux determination was checked by a fixed C2 plate in which the conventional proton recoil method was used. Good agreement was obtained.

100‐micron E1 and C2 Ilford plates loaded with enriched Li6 were exposed to neutrons from Li7(p, n)Be7 and from H3(p, n)He3. The plates were rotated to mockup isotropic incidence. Neutron energies ranged from 200 to 1500 kev. The plates were faded and developed so as to obtain good triton‐alpha discrimination. Peaks having widths from 100 to 300 kev at half‐maximum were obtained, depending upon neutron energy and selection criteria.

Type E1 Ilford emulsions loaded with specks of Li6 glass were studied for the measurement of neutron spectra from ∼50 to 1000 kev. The method is independent of the neutron directions. Resolutions of about 200 kev were obtained. Calibrations were made by exposure to monoergic neutrons at several energies, and the method was tested by neutron spectra determined independently from fission and ``long counter'' data. The theory of the reduction of track data to neutron spectra is given. The results look promising for application to the measurement of neutron spectra in fast critical assemblies and for similar problems.

A study of hyperfragments has been made in a 10-inch3 stack of Ilford G5 emulsion which was exposed to the Berkeley 4.7 GeV/c π- beam. In area scanning 66 500 interaction stars, 37 hyperfragments (12 mesonic decays - 25 non-mesonic decays) and 61 other secondary events (« Goks ») with connecting tracks < 15 μm were found. Some fraction of these 61 GOKS (undetermined in this study) represent hyperfragments. Binding energies for 6 of the mesonic hyperfragments have been obtained. Three of these binding energies are forZ ⩾ 3.

The domain of Solid State Track Recorder (SSTR) applications in United States nuclear reactor energy programs extends from the harsh high temperature environments found in high power reactor cores to very low flux environments arising in out-of-core locations, critical assemblies, or away from reactors (AFR) experiments. The neutron energy region arising in these applications is very broad, covering more than eight decades from thermal up to fusion energies. The range of neutron flux/fluence intensity is even greater, extending over more than thirteen decades. As a consequence, use of a variety of SSTR is entailed in U.S. Fast Breeder Reactor (FBR), Light Water Reactor (LWR), and Magnetic Fusion Energy Reactor (MFER) programs. A summary status is presented of selected SSTR experiments undertaken in these programs at the Hanford Engineering Development Laboratory (HEDL).