Coincidence electron scattering (e,e'f) and multipole strength functions in /sup 238/U

Conference · Tue Jan 15 04:00:00 EST 1985 · AIP Conf. Proc.; (United States)

OSTI ID:5709989

Griffioen, K A; Countryman, P J; Knoepfle, K T; Van Bibber, K; Yearian, M R; Woodworth, J G; Rowley, D; Calarco, J R

The inherent power of inelastic scattering to probe the nuclear response function in the nuclear continuum is completely exploited only in the coincident detection of decay products. The coincidence requirement effectively eliminates the strong elastic radiative tail which hitherto plagued the analysis of single arm (e,e') experiments. Large physical backgrounds (e.g. due to multistep processes as encountered in inelastic hadron scattering) are negligible due to the dominance of single photon exchange. Thus, coincidence electron scattering is a unique tool for quantitatively testing modern calculations of the nuclear response function. We have measured /sup 238/U(e,e'f) cross sections at three values of the momentum transfer (qapprox. =0.26, 0.40, and 0.55 fm/sup -1/, which correspond closely to the first maxima of the E1, E2/E0, and E3 form factors respectively) from below fission threshold to 23 MeV excitation energy. The angular correlations were measured at six or seven angles in each run. The data permit a clear multipole decomposition and a rigorous comparison with recent theoretical results from the Quasiparticle Random Phase Approximation (QRPA). The extracted E1 strength function agrees well with photofission results. The E2/E0 distribution displays prominent resonances at 10 and 13 MeV which suggest an identification with collective isoscalar E2 and E0 strength respectively, as predicted within the QRPA. However, the observed E2 strength is anomalously low, corroborating some earlier (..cap alpha..,..cap alpha..'f) reports. E2 and higher order multipoles contribute a sizable amount of strength in the region from 5 to 17 MeV.

• Research Organization: Department of Physics and High Energy Physics Laboratory, Stanford University, Stanford, CA 94305
• OSTI ID: 5709989
• Report Number(s): CONF-840906-
• Conference Information: Journal Name: AIP Conf. Proc.; (United States) Journal Volume: 125:1
• Country of Publication: United States
• Language: English

Related Subjects

652020* -- Nuclear Properties & Reactions
A=220 & above
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
CHARGED-PARTICLE REACTIONS
COINCIDENCE METHODS
COUNTING TECHNIQUES
CROSS SECTIONS
DISTRIBUTION
E1-TRANSITIONS
E2-TRANSITIONS
ELECTRON REACTIONS
ENERGY-LEVEL TRANSITIONS
FISSION
FUNCTIONS
INELASTIC SCATTERING
LEPTON REACTIONS
MULTIPOLE TRANSITIONS
NUCLEAR REACTIONS
RANDOM PHASE APPROXIMATION
RESPONSE FUNCTIONS
SCATTERING
TARGETS
URANIUM 238 TARGET