Characterization of a tagged γ-ray beam line at the DAΦNE Beam Test Facility (meglio tardi che mai…)

P.W. Cattaneo^g, A. Argan^a^,^p^,^t, F. Boffelli^g, A. Bulgarelli^e, B. Buonomo^u, A.W. Chen^c^,^d, F. D’Ammando^v, L. Foggetta^d^,¹, T. Froysland^b^,^d, F. Fuschino^e, M. Galli^h, F. Gianotti^e, A. Giuliani^c, F. Longo^f, M. Marisaldi^e, G. Mazzitelli^u, A. Pellizzoni^r, M. Prest^l, G. Pucella^m, L. Quintieri^u, A. Rappoldi^g, M. Tavani^a^,^b, M. Trifoglio^e, A. Trois^r, P. Valenteⁱ, E. Vallazza^f, S. Vercellone^s, A. Zambra^c, G. Barbiellini^f, P. Caraveo^c, V. Cocco^a, E. Costa^a, G. De Paris^a, E. Del Monte^a, G. Di Cocco^e, I Donnarumma^a, Y. Evangelista^a, M. Feroci^a, A. Ferrari^d^,^q, M. Fiorini^c, C. Labanti^e, I. Lapshov^a, F. Lazzarotto^a, P. Lipariⁱ, M. Mastropietro^j, S. Mereghetti^c, E. Morelli^e, E. Moretti^f, A. Morselli^k, L. Pacciani^a, F. Perotti^c, G. Piano^a^,^b^,^k, P. Picozza^b^,^k, M. Pilia^l, G. Porrovecchio^a, M. Rapisarda^m, A. Rubini^a, S. Sabatini^a^,^b,P. Soffitta^a, E. Striani^b^,^k, V. Vittorini^a^,^b, D. Zanelloⁱ, S. Colafrancescoⁿ, P. Giommiⁿ, C. Pittoriⁿ, P. Santolamazzaⁿ, F. Verrecchiaⁿ, L. Salotti^o

^a INAF/IASF-Roma, I-00133 Roma, Italy^b Dip. di Fisica, Univ. Tor Vergata, I-00133 Roma, Italy^c INAF/IASF-Milano, I-20133 Milano, Italy^d CIFS-Torino, I-10133 Torino, Italy^e INAF/IASF-Bologna, I-40129 Bologna, Italy^f INFN Trieste, I-34127 Trieste, Italy^g INFN-Pavia, I-27100 Pavia, Italy^h ENEA-Bologna, I-40129 Bologna, Italyⁱ INFN-Roma La Sapienza, I-00185 Roma, Italy^j CNR-IMIP, Roma, Italy^k INFN Roma Tor Vergata, I-00133 Roma, Italy^l Dip. di Fisica, Univ. Dell’Insubria, I-22100 Como, Italy^m ENEA Frascati, I-00044 Frascati (Roma), Italyⁿ ASI Science Data Center, I-00044 Frascati (Roma), Italy^o Agenzia Spaziale Italiana, I-00198 Roma, Italy^p Osservatorio Astronomico di Trieste, Trieste, Italy^q Dip. Fisica, Universitá di Torino, Torino, Italy^r INAF-Osservatorio Astronomico di Cagliari, localita’ Poggio dei Pini, strada 54, I-09012 Capoterra, Italy^s INAF-IASF Palermo, Via Ugo La Malfa 153, I-90146 Palermo, Italy^t Dip. Fisica Univ. di Trieste, I-34127 Trieste, Italy^u INFN Lab. Naz. di Frascati, I-00044 Frascati (Roma), Italy^v INAF-IRA Bologna, Via Gobetti 101, I-40129 Bologna, Italy

Received 25 November 2011. Revised 16 January 2012. Accepted 19 January 2012. Available online 27 January 2012.

http://dx.doi.org/10.1016/j.nima.2012.01.049

Abstract

At the core of the AGILE scientific instrument, designed to operate on a satellite, there is the Gamma Ray Imaging Detector (GRID) consisting of a Silicon Tracker (ST), a Cesium Iodide Mini-Calorimeter and an Anti-Coincidence system of plastic scintillator bars. The ST needs an on-ground calibration with a γ-ray beam to validate the simulation used to calculate the energy response function and the effective area versus the energy and the direction of the γ rays. A tagged γ-ray beam line was designed at the Beam Test Facility (BTF) of the INFN Laboratori Nazionali of Frascati (LNF), based on an electron beam generating γ-rays through bremsstrahlung in a position-sensitive target. The γ-ray energy is deduced by difference with the post-bremsstrahlung electron energy [1] and [2]. The electron energy is measured by a spectrometer consisting of a dipole magnet and an array of position sensitive silicon strip detectors, the Photon Tagging System (PTS). The use of the combined BTF-PTS system as tagged photon beam requires understanding the efficiency of γ-ray tagging, the probability of fake tagging, the energy resolution and the relation of the PTS hit position versus the γ-ray energy. This paper describes this study comparing data taken during the AGILE calibration occurred in 2005 with simulation.