Gai, M.
Ahmed, M.W.
Stave, S.C.
Zimmerman, W.R.
Breskin, A.
Bromberger, B.
Chechik, R.
Dangendorf, V.
Delbar, Thierry
[UCL]
France III, R.H.
Henshaw, S.S.
Kading, T.J.
Martel, P.P.
McDonald, J.E.R.
Seo, P.-N.
Tittelmeier, K.
Weller, H.R.
Young, A.H.
We report on the construction, tests, calibrations and commissioning of an Optical Readout Time Projection Chamber (O-TPC) detector operating with a CO2(80%) + N2(20%) gas mixture at 100 and 150 Torr. It was designed to measure the cross sections of several key nuclear reactions involved in stellar evolution. In particular, a study of the rate of formation of oxygen and carbon during the process of helium burning will be performed by exposing the chamber gas to intense nearly mono-energetic gamma-ray beams at the High Intensity Gamma Source (HIγS) facility. The O-TPC has a sensitive target-drift volume of 30x30x21 cm3. Ionization electrons drift towards a double parallel-grid avalanche multiplier, yielding charge multiplication and light emission. Avalanche-induced photons from N2 emission are collected, intensified and recorded with a Charge Coupled Device (CCD) camera, providing two-dimensional track images. The event's time projection (third coordinate) and the deposited energy are recorded by photomultipliers and by the TPC charge-signal, respectively. A dedicated VME-based data acquisition system and associated data analysis tools were developed to record and analyze these data. The O-TPC has been tested and calibrated with 3.183 MeV alpha-particles emitted by a 148Gd source placed within its volume with a measured energy resolution of 3.0%. Tracks of alpha and 12C particles from the dissociation of 16O and of three alpha-particles from the dissociation of 12C have been measured during initial in-beam test experiments performed at the HIγS facility at Duke University. The full detection system and its performance are described and the results of the preliminary in-beam test experiments are reported. © 2010 IOP Publishing Ltd and SISSA.
Bibliographic reference |
Gai, M. ; Ahmed, M.W. ; Stave, S.C. ; Zimmerman, W.R. ; Breskin, A. ; et. al. An Optical Readout TPC (O-TPC) for studies in nuclear astrophysics with gamma-ray beams at HIγS. In: Journal of Instrumentation, Vol. 5, no. 12 (2010) |
Permanent URL |
http://hdl.handle.net/2078.1/163747 |