Si25andS29studied via single neutron knockout rea

Abstract

The γ -ray spectroscopy of 25 Si and 29 S has been performed using single neutron knockout reactions with intermediate energy beams of the exotic isotopes 26 Si and 30 S. Two γ rays have been observed in 25 Si and three in 29 S. These are the first γ rays observed in these two isotopes. These two nuclei appear to be well deformed, and possible future intermediate-energy Coulomb excitation measurements would confirm their rotational nature.

Measurement of key resonances for the Al24(p,γ)Si25 reaction rate using in-beam Longfellow1, Gade2, Brown3 et al. 2018Phys. Rev. CSelf Cite

“…At the beginning of the rp process, there is breakout from the hot CNO cycle into the Ne-Na region. The flow out of the NeNa cycle proceeds via chains involving the reaction 24 Al(p,γ) 25 Si [2,8]. Not much is known about excited states in 25 Si, in particular those relevant to the reaction rate calculation just above the proton separation energy of S p = 3414(10) keV [9].…”

“…The flow out of the NeNa cycle proceeds via chains involving the reaction 24 Al(p,γ) 25 Si [2,8]. Not much is known about excited states in 25 Si, in particular those relevant to the reaction rate calculation just above the proton separation energy of S p = 3414(10) keV [9]. 25 Si has been studied by Benenson et al using the 28 Si( 3 He, 6 He) 25 Si reaction, which populated one state in the relevant energy range at 3820 (20) keV with unmeasured spin-parity [10].…”

A Rapidly Spinning Black Hole Powers the Einstein Cross

“…Direct constraints on the spin of a black hole are now possible via modeling the accretion disk reflection spectrum (Lightman & White 1988;Fabian et al 1989;Tanaka et al 1995;Miller 2007). Detailed observations of AGN in the local universe (z 0.1) illustrate the power of this method to constrain the inner accretion flow geometry in the strong GR regime through both spectral (e.g., Fabian et al 2009;Risaliti et al 2013;Reynolds 2013) and timing methods (e.g., Zoghbi et al 2012;De Marco et al 2013;Kara et al 2013;Uttley et al 2014). However, at the current time it is only possible to indirectly probe the spin distribution for black holes at high redshift (Davis & Laor 2011;Wu et al 2013 Trakhtenbrot 2014), though such methods are necessarily hampered by substantial systematic uncertainties, e.g., Raimundo et al (2012).…”

Evolution of single-particle structure of silicon isotopes

“…However, probable splitting caused by the deformed potential, the states of rotational and vibrational origin make it more uncertain and vague. Information on the excited states is available only for 25−39 Si, as long as the spinparity of the only excited state in 41 Si has not been identified yet [40].…”

“…The excited-state spectrum for 25 Si is too scanty to define the single-particle states in 26 Si. The most sufficient and reliable information on the structure of 25 Si was gathered in the reaction 9 Be( 26 Si, 25 Si)X [41]. Comparison of the experimental results and the shell model predictions proved the first excited state E 1 (1/2 + ) = 0.821 MeV to be one of the rotational levels.…”