Doubly RadiativenpCapture

We have calculated the cross section for n+p --c d +2y. This process depends critically on the same matrix element that gives the amplitude for singly radiative np capture from the continuum 3 S state. It has been suggested that 1’anomalous17 transitions from this continuum 3S state may explain a long-standing discrepancy in np capture ((T =334.2*.5 mb and 0 exp th = 309.5 % 5 mb) by contributing roughly 8% to the total np capture cross section. If this speculation is correct then the branching ratio of doubly to singly radiative np capture is 1.4 x 10 -4 . On the other hand a conventional estimate of this amplitude yields a branching ratio of about 3.4 x 10 -lo. An experimental measurement of the doubly radiative cross section in the 10 pb region should therefore settle the question of the importance of the 3S initial state in the total radiative np capture cross section. Such a measurement seems at present to be much easier than similarly motivated polarization measurements. ?: Supported in part by the National Science Foundation, Grant GP-16565, and in part by the U. S. Atomic Energy Commission. \ SLAC-PUB-1035 V-H) April 1972 DOUBLY RADIATIVE np CAPTURE? Ronald J. Adler The American University Washington, D. C. 20016 and Stanford Linear Accelerator Center Stanford University, Stanford, California 94305 ABSTRACT We have calculated the cross section for n+pd+2y. This process depends critically on the same matrix element that gives the amplitude for singly radiative np capture from the continuum 3 S state. It has been suggested that “anomalous” transitions from this continuum 3S state may explain a long-standing discrepancy in np capture (a exp334.2~ .5 mb and ath =309.5& 5 mb) by contributing roughly 8% to the total np capture cross section. If this speculation is correct then the branching ratio of doubly to singly radiative np capture is 1.4 x 10 -4 . On the other hand a conventional estimate of this amplitude yields a branching ratio of about 3.4x 10 -10 . An experimental measurement of the doubly radiative cross section in the 10 pb region should therefore settle the question of the importance of the 3S initial state in the total radiative np capture cross section. Such a measurement seems at present to be much easier than similarly motivated polarization measurements.We have calculated the cross section for n+pd+2y. This process depends critically on the same matrix element that gives the amplitude for singly radiative np capture from the continuum 3 S state. It has been suggested that “anomalous” transitions from this continuum 3S state may explain a long-standing discrepancy in np capture (a exp334.2~ .5 mb and ath =309.5& 5 mb) by contributing roughly 8% to the total np capture cross section. If this speculation is correct then the branching ratio of doubly to singly radiative np capture is 1.4 x 10 -4 . On the other hand a conventional estimate of this amplitude yields a branching ratio of about 3.4x 10 -10 . An experimental measurement of the doubly radiative cross section in the 10 pb region should therefore settle the question of the importance of the 3S initial state in the total radiative np capture cross section. Such a measurement seems at present to be much easier than similarly motivated polarization measurements. “r Supported in part by the National Science Foundation, Grant GP-16565, and in part by the U. S. Atomic Energy Commission. (Submitted to Phys. Rev.)