29 October 2018 to 2 November 2018
Protea Hotel Fire & Ice
Africa/Johannesburg timezone
Registration closes on 17 October

Are the Molybdenums Fluffy Too?

Not scheduled
20m
Protea Hotel Fire & Ice

Protea Hotel Fire & Ice

64 New Church Street, Tamboerskloof Cape Town 8001
Oral Track A

Speaker

Mr Kevin B. Howard (University of Notre Dame)

Description

"Why are the tin isotopes fluffy?" has remained, for nearly a decade, a fundamental open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the “standard" doubly-closed shell nuclei, $^{90}$Zr, $^{208}$Pb, overestimate, by as much as 1 MeV, the ISGMR energies of the open-shell tin and cadmium nuclei [1-4].

To further elucidate this question as also to examine when this “fluffiness" appears in moving away from the doubly-closed nucleus $^{90}$Zr, and how this effect develops, we have carried out measurements of the isoscalar giant resonance strength distributions in a series of molybdenum nuclei. The measurements were performed for $^{94,96,97,98,100}$Mo, using inelastic scattering of 100 MeV/u $\alpha$ particles at the Research Center for Nuclear Physics, Osaka University. The targets, with thicknesses $\sim$ 5 mg/cm$^2$, were enriched to an isotopic purity of approximately 95%. The measurements on all nuclei were performed within the same experiment so as to minimize any systematic effects in the final results. The versatile, high-precision mass spectrometer, Grand Raiden, provided small angle ($0-10^\circ$) spectra virtually free of all instrumental background. The resulting double-differential cross sections can be used to reliably extract ISGMR strength distributions using a multipole decomposition analysis; this procedure is currently in progress. The extracted ISGMR strengths will be presented. It is hoped that these results, in combination with previously published results for the ISGMR strength in $^{90,92}$Zr and $^{92}$Mo [5], will provide important information for possible refinements of theoretical models in describing this mode in open- and closed-shell nuclei alike.

This work has been supported in part by the National Science Foundation (Grant Nos. PHY-1713857 and PHY-1419765), and by the Liu Institute for Asia and Asian Studies, University of Notre Dame.

References:
[1] U. Garg, et al. Nucl. Phys. A, 788, 36. (2007)
[2] J. Piekarewicz, J. Phys. G: Nucl. Part. Phys, 37, 064038. (2010)
[3] L.G. Cao et al. Phys. Rev. C, 86, 054313. (2012)
[4] P. Vesely et al. Phys. Rev. C, 86, 024303. (2012)
[5] Y.K. Gupta et al. Phys. Lett. B, 760, 482. (2016)

Primary author

Mr Kevin B. Howard (University of Notre Dame)

Co-authors

Prof. Umesh Garg (University of Notre Dame) Mr Yilong Yang (University of Notre Dame) Dr Menekse Senyigit (Ankara University) Prof. Masatoshi Itoh (Tohoku University) Prof. Shinsuke Ota (Center for Nuclear Study, University of Tokyo) Prof. Hidetoshi Akimune (Konan University) Prof. Mamoru Fujiwara (Osaka University) Prof. Takahiro Kawabata (Osaka University) Prof. Muhsin N. Harakeh (KVI-CART, University of Groningen) Dr Yohei Matsuda (Tohoku University) Mr Tatsuya Furuno (Kyoto University) Miho Tsumura (Kyoto University) Mr Motoki Murata (Kyoto University) Ms Akane Sakaue (Kyoto University) Mr Kento Inaba (Kyoto University) Mr Kouhei Karasudani (Tohoku University) Mr Asahi Kohda (Osaka University) Mr Shoken Nakamura (Osaka University) Mr Jun Okamoto (Tohoku University) Mr Yoko Ishibashi (Tohoku University)

Presentation Materials