1. INDIRECT DETERMINATION OF NEUTRON CAPTURE CROSS SECTIONS ON SPHERICAL AND NEAR-SPHERICAL NUCLEI USING THE SURROGATE METHOD Bethany L. Goldblum Berkeley Nuclear Research Center Department of Nuclear Engineering University of California, Berkeley

2. T HE S URROGATE M ETHOD Nuclear Reactions Schematic 93 Mo * PnPn PP n Desired Reaction d Direct Reaction p 92 Mo 92 Mo(d,p  )  93 Mo  92 Mo(n,  ) 94 Mo(d,p  )  95 Mo  94 Mo(n,  )

3. M ETHODOLOGY Absolute Surrogate Measurement Surrogate Ratio Measurement

4. E XPERIMENTAL M ETHODS STARS-LiBerACE 11 MeV Deuteron Beam 92 Mo: 460 ± 5 μg/cm 2 Target-  E spacing: 9 mm 94 Mo: 250 ± 6 μg/cm 2 Target-  E spacing: 21 mm

5. Discrete  -ray Tagging Statistical  -ray Tagging IDENTIFICATION OF THE NUMBER OF  -CASCADES IN COINCIDENCE WITH THE SURROGATE REACTION EJECTILE

6. Discrete  -ray Tagging Statistical  -ray Tagging IDENTIFICATION OF THE NUMBER OF  -CASCADES IN COINCIDENCE WITH THE SURROGATE REACTION EJECTILE Energy (keV) 93 Mo: E peak = 943 keV E x = 8000-8100 keV

7. IDENTIFICATION OF THE NUMBER OF  -CASCADES IN COINCIDENCE WITH THE SURROGATE REACTION EJECTILE Discrete  -ray Tagging Statistical  -ray Tagging Energy (keV) 93 Mo: E  = 6-7 MeV E x = 8000-8100 keV

8. 92 M o ( n,  ) C ROSS S ECTION Absolute Surrogate Measurement

9. 92 M o ( n,  ) C ROSS S ECTION Surrogate Ratio Measurement

10. E VALUATION OF  - DECAY TAGGING TECHNIQUES  -decay probability of 93 Mo and 95 Mo

11. E VALUATION OF  - DECAY TAGGING TECHNIQUES Ratio of the Statistical to Discrete Tag

12. CONCLUSIONS 1.First use of the surrogate method in the indirect determination of neutron-induced reaction cross sections on spherical and quasi-spherical nuclei 1.To improve the discrete tag, empirical data on nuclear level schemes could be used to sum parallel decay paths 2.To improve the statistical tag, the  -ray energy range should be constrained to isolate primary  -transitions 3.Discrete and statistical  -decay tags likely capture similar information for more deformed nuclei B.L. Goldblum, et al., Phys. Rev C 85, 054616 (2012). 1.First use of the surrogate method in the indirect determination of neutron-induced reaction cross sections on spherical and quasi-spherical nuclei 1.To improve the discrete tag, empirical data on nuclear level schemes could be used to sum parallel decay paths 2.To improve the statistical tag, the  -ray energy range should be constrained to isolate primary  -transitions 3.Discrete and statistical  -decay tags likely capture similar information for more deformed nuclei B.L. Goldblum, et al., Phys. Rev C 85, 054616 (2012).

13. COLLABORATORS M. Wiedeking, L.A. Bernstein, D.L. Bleuel, F.S. Dietrich, R. Hatarik, S.R. Lesher, N.D. Scielzo P.T. Lake, I.-Y. Lee, S. Pachalis, M. Petri, L. Phair K. Alfonso, R. Vial, J. Vujic T. Reed J.M. Allmond