STUDY OF THE K CAPTURE--POSITRON RATIO OF THE TRANSITION I$sup 126$ (2-) $Yields$ Te$sup 126$(2+)
The relative probabilities of K-electron capture and of positron emission have been measured for the transition of I/sup 126/(2-)to the first excited state of Te/sup 126/(2+). Direct measurement by a triple-coincidence method of the K/ BETA /sup +/ ratio gave the value 145 plus or minus 4. The energy of the positron transition to the ground state (2-- yields 0+) was found to be l.129 plus or minus 0.005 Mev. The energy of the inaer positron transition was determined to be 0.459 plus or minus 0.007 Mev by subtraction of the measured energy of the firstexcited state of Te/sup 126/, 0.670 plus or minus 0.005 Mev, from the ground-state-transition energy. The K/ BETA I ratio of the 2-- yields 2+ transition and the ratios for analogous transitions occurring in As/sup 7/ and Rb/sup 84/ are compared with ratios computed from a model based on shell considerations. Measurements were made also of the two higher energy positron spectra of I/sup 124/; the end-point energies were found to be 2.136 plus or minus 0.0l0 Mev and 1.53 plus or minus 0.02 Mev. (auth) l8547 The ( gamma ,p), ( gamma ,np), ( gamma ,n), and ( gamma ,2n) cross sections for Ar/sup 40/ are presented. The ( gamma ,p) cross section has a peak at 23.5 Mev while the ( gamma ,n) cross section peaks at 16.5 Mev and the ( gamma ,2n) peaks at 20 Mev. The ( gamma ,np) cross section peaks at 27.5 Mev. The total absorption cross section fof Ar/sup 40/ has a peak height of 86 mb at 23.5 Mev and a full width at half maximum of 10.3 Mev. The integrated total cross section is 470 plus or minus 70 mb-Mev to 23 Mev and 900 plus or minus 180 mb-Mev to 40 Mev. The shapes of these cross sections are discussed and a need for further investigation of energy and angular distributions of photoprotons from argon is indicated. (auth) Energy spectra of deuterons and tritons from (p,d) and (p,t) reactions are found to be peaked near their maximum energy, in contrast to the spectra of protons from (d,p) and (t,p) reactions which are peaked at low energy. It is shown that this characteristic of inverse reactions is to be expected from stripping'' and 'pickup'' reactions as a consequence of the fact that the former excite 'particle'' states while the latter excite hole'' states, but that is not expected from collision type reaction mechanisms (e.g., knockout''). It is thus concluded that (t,p) and (p,t) reactions as well as (d,p) and (p,d) reactions proceed by ''stripping'' and pickup.' The shape of energy spectra from (p, alpha ) and ( alpha ,p) reactions indicates that the non-compound- nucleus portion of these also goes by pickup'' and stripping;'' there is corroboratory evidence for this from absolute cross sections. (auth)
- Research Organization:
- Brookhaven National Lab., Upton, N.Y.
- NSA Number:
- NSA-13-018546
- OSTI ID:
- 4258570
- Journal Information:
- Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 114; ISSN PHRVA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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