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AstroBox - a new detection system for very low-energy protons from -delayed p-decayAlexandra SpiridonCyclotron InstituteTexas A&M UniversityAcknowledgementsCyclotron Institute, Texas A&M University L. Trache E. Simmons M. McCleskeyB.T. RoederR.E. Tribble

CEA SaclayE. PollaccoMarc RiallotJean Philipe MolsMariam Kebbiri IKP KlnG. Pascovici

Decay spectroscopyBeta- and beta-delayed proton-decay&IAS in Tz=-3/2 nucleiIsospin mixingGT strength distributionExplosive H-burning in novae22Na depletion in novae23Al23Mg* 22Na(p,g)23Mg*bottleneck r. in novae31Cl31S* 30P(p,g)31S*33Dr. Trache mentioned in his talk this morning that one of the indirect methods for determining astrophysical reaction rates is decay spectroscopy. In particular at TAMU weve been studying resonant capture by looking at beta and beta-delayed proton decay.

Experimental setup Before

The way we did this was by using a so-called sandwich setup of silicon detectors. In the middle we put a proton detector, 45 or 65 um Si strip det. Behind and sometimes in front, as well, we put a beta detector, a Si pad, 1mm thick. On the side, we placed one or two HPGe detectors for gamma measurements. The silicon detectors were placed at 45 degrees. A rotating aluminum degrader was used for implantation purposes. The idea behind this was to separate the radioisotope of interest with the spectrometer and then implant the beam obtained in the proton detector. With the setup as such we could then measure bg and bp coincidences.5

5/2+7/2+IAS

Lower beta backgroundBetter energy resolution

One of the successful applications of this was in the study of the beta-delayed proton decay of 23Al. You can see here the b-gated gamma spectrum.6New detection setup - AstroBox

New detection setup - AstroBox

23Al 40A MeV

24Mg 45A MeV

Primary beam 24Mg @ 45A MeV K500 CyclPrimary target LN2 cooled H2 gas p=2 atm Secondary beam 23Al @ 40.2A MeV Purity: ~90%Intensity: ~ 4000 ppsFirst time - very pure & intense 23AlIsotope separation - MARS

Implantation procedure Now

Measurements

Results Detection efficiency

AstroBox - Results

206 keV267579866betasCan go to Ep~80 keVGood peak separationVery sensitive clear results within just ~2 hrs of statistics

Thank you for your attention!

19Implantation procedure Before