title: Neutron yields from 435 MeV/nucleon Nb stopping in Nb and 272 MeV/nucleon Nb stopping in Nb and Al.
abstract: Neutron fluences were measured from 435 MeV/nucleon Nb ions stopping in a Nb target and 272 MeV/nucleon Nb ions stopping in targets of Nb and Al for neutrons above 20 MeV and at laboratory angles between 3 degrees and 80 degrees. The resultant spectra were integrated over angles to produce neutron energy distributions and over energy to produce neutron angular distributions. The total neutron yields for each system were obtained by integrating over the angular distributions. The angular distributions from all three systems are peaked forward, and the energy distributions from all three systems show an appreciable yield of neutrons with velocities greater than the beam velocity. Comparison of the total neutron yields from the two Nb + Nb systems suggests that the average neutron multiplicity decreases with decreasing projectile energy. Comparison of the total yields from the two 272 MeV/nucleon systems suggests that the total yields show the same dependence on projectile and target mass number as do total inclusive neutron cross sections. The data are compared with Boltzmann-Uehling-Uhlenbeck model calculations.
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: L
authors.initials: L
authors.lastname: Heilbronn
authors.forename: R
authors.initials: R
authors.lastname: Madey
authors.forename: M
authors.initials: M
authors.lastname: Elaasar
authors.forename: M
authors.initials: M
authors.lastname: Htun
authors.forename: K
authors.initials: K
authors.lastname: Frankel
authors.forename: W G
authors.initials: WG
authors.lastname: Gong
authors.forename: B D
authors.initials: BD
authors.lastname: Anderson
authors.forename: A R
authors.initials: AR
authors.lastname: Baldwin
authors.forename: J
authors.initials: J
authors.lastname: Jiang
authors.forename: D
authors.initials: D
authors.lastname: Keane
authors.forename: M A
authors.initials: MA
authors.lastname: McMahan
authors.forename: W H
authors.initials: WH
authors.lastname: Rathbun
authors.forename: A
authors.initials: A
authors.lastname: Scott
authors.forename: Y
authors.initials: Y
authors.lastname: Shao
authors.forename: J W
authors.initials: JW
authors.lastname: Watson
authors.forename: G D
authors.initials: GD
authors.lastname: Westfall
authors.forename: S
authors.initials: S
authors.lastname: Yennello
authors.forename: W M
authors.initials: WM
authors.lastname: Zhang
mesh_terms: D000535:Aluminum; D003359:Cosmic Radiation; D019471:Elementary Particle Interactions; D004601:Elementary Particles; D004735:Energy Transfer; D008962:Models, Theoretical; D009502:Neutrons; D009556:Niobium; D011835:Radiation Protection; D013057:Spectrum Analysis
chemical_list: D009556:Niobium; D000535:Aluminum