Excited states in 22 Mg via the 12 C( 12 C, 2n) 22 Mg reaction C. Jewett a , C. Baktash b , D. Bardayan b , J. Blackmon b , K. Chipps a , A. Galindo-Uribarri b , U. Greife a, * , C. Gross b , K. Jones d , F. Liang b , J. Livesay a , R. Kozub c , C. Nesaraja c , D. Radford b , F. Sarazin a , M.S. Smith b , J. Thomas d , C.-H. Yu b a Department of Physics, Colorado School of Mines, Golden, CO, USA b Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA c Department of Physics, Tennessee Tech University, Cookeville, TN, USA d Department of Physics, Rutgers University, Piscataway, NJ, USA Available online 28 March 2007 Abstract The 12 C( 12 C, 2n) 22 Mg reaction was measured with the CLARION array and the RMS separator at the Holifield Facility of Oak Ridge National Laboratory. This experiment was performed to gather more information on the excited states in 22 Mg, which might be of rel- evance to recent radioactive ion beam measurements of the astrophysically important 21 Na(p, c) 22 Mg reaction. The results are compared to direct measurements, transfer experiments and a competing experiment performed with Gammasphere. Ó 2007 Elsevier B.V. All rights reserved. PACS: 25.60.t; 26.30.+k Keywords: Excited states; Astrophysically relevant 1. Introduction One of the first experiments with radioactive ion beam at the ISAC facility of TRIUMF in Vancouver was the measurement of the reaction rate of 21 Na(p, c) 22 Mg in the energy regime of importance for explosive stellar scenarios in novae and possible X-ray bursts [1,2]. The range in ener- gies in 22 Mg probably involved, reach from the proton threshold to excitation energies of about 6.5 MeV. The astrophysical reaction rate for radiative capture reactions in this energy regime is usually dominated by res- onances. Due to the low beam currents available at radio- active ion beam facilities (and restrictions in beam time) it is impractical or impossible to measure complete excitation functions. It is thus necessary to study the levels in the rel- evant reaction product or compound nucleus beforehand. In the case of the 21 Na(p, c) 22 Mg reaction the levels of 22 Mg were studied in detail prior to the RIB experiment via transfer reactions including (p, t) and ( 3 He, n) reactions [3–6] and an elastic scattering experiment [7]. Nevertheless, many spin assignments remained ambiguous and several states expected from more complete studies of the mirror nucleus 22 Ne have not yet been found. The situation was recently reviewed in a publication by Fortune et al. [8]. In the past two years the DRAGON experiment at ISAC measured the 21 Na(p, c) 22 Mg reaction at all energies where resonant levels were predicted [2]. While resonant yield was detected for most of the states expected, the state previously measured by one experiment [9] at 5.837 MeV, which is of particular interest due to its low energy, could not be confirmed in the (p, c) channel. One reason for this could be lack of precision in the knowledge of the level energy. Additionally, the resonance energy of the astro- physically most important state (5714 keV[3]) was mea- sured 6 keV lower than predicted. The reason for this discrepancy could lie in the reaction Q-value (masses) and/or the previous measurement of the excitation energy. 0168-583X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2007.03.022 * Corresponding author. Tel.: +1 303 273 3618; fax: +1 303 273 3919. E-mail address: ugreife@mines.edu (U. Greife). www.elsevier.com/locate/nimb Nuclear Instruments and Methods in Physics Research B 261 (2007) 945–947 NIM B Beam Interactions with Materials & Atoms