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Abstract |
We describe the data analysis methods and the characteristics of the combined set-up of the gamma -ray tracking spectrometer AGATA with two annular double sided silicon strip detectors (DSSD) (4" diameter) placed 5.65 cm upstream and downstream of the target, for the measurement of gamma -light particle coincidences in near- and sub-barrier heavy-ion fusion reactions. The DSSD cover the angular ranges theta lab=139.6o – 162.7o and =23.0o – 40.4o , corresponding to a total solid angle similar or equal to 26% of 4 pi . The ohmic side of the DSSD is turned towards the target, so protons and alpha particles can be clearly identified. We show the relevant results obtained for the two systems 28 Si+ 12 C and 16 O+ 12 C down to very small cross sections in the tenths of nb range. Particle identification allows us to observe well-separated groups of protons and alpha 's populating low-energy levels of the various fusion-evaporation residues (ER). Relative fusion cross sections are obtained with a procedure described in detail, and the absolute cross section scale is fixed by complementary measurements using an electrostatic beam deflector set-up where the ER are directly detected down to a few μb. The AGATA+DSSD set-up is subject to significant improvements thanks to the scheduled increase of the number of gamma detectors, and to the possibility of installing silicon detector arrays covering a larger solid angle. This will open the possibility of measuring fusion cross sections near, and possibly below, 1nb. |
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Address |
[Del Fabbro, M.; Mijatovic, T.; Szilner, S.] Rudjer Boskovic Inst, HR-10002 Zagreb, Croatia; [Montagnoli, G.; Mengoni, D.; Pellumaj, J.; Pigliapoco, S.] Univ Padua, Dipartimento Fis & Astron, I-35131 Padua, Italy; [Montagnoli, G.; Mengoni, D.; Pellumaj, J.; Pigliapoco, S.] INFN, Sez Padova, Padua, Italy; [Stefanini, A. M.; Balogh, M.; Brugnara, D.; Corradi, L.; Carletto, O.; Fioretto, E.; Goasduff, A.; Gottardo, A.; Loriggiola, M.; Toniolo, N.; Valiente-Dobon, J. J.; Zago, L.] INFN, Lab Nazl Legnaro, I-35020 Legnaro, Padova, Italy; [Colucci, G.] Univ Warsaw, Heavy Ion Lab, PL-02093 Warsaw, Poland; [Galtarossa, F.] INFN, Sez Padova, I-35131 Padua, Italy; [Valiente-Dobon, J. J.] Univ Valencia, CSIC, Inst Fis Corpuscular, Valencia 46980, Spain, Email: alberto.stefanini@lnl.infn.it |
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