The SpecMAT Project: An array of gamma ray detectors around an active target J. A. Swartz, R. Raabe & H. De Witte ANSRI Workshop, University College Dublin 14/01/2015
The SpecMAT project (ERC grant, R. Raabe) To investigate exotic nuclei, specifically neutron-rich around Z = 28, e.g. 68, 70Ni; 78, 80Zn neutron-deficient around Z = 82, e.g. 184Hg, 188Pb, 196Po stable nuclei observed nuclei unknown nuclei (predicted) 82 Pb 208 50 126 78 28 20 50 8 28 20 28 Ni 82
The SpecMAT project (ERC grant, R. Raabe) To investigate exotic nuclei, specifically neutron-rich around Z = 28, e.g. 68, 70Ni; 78, 80Zn neutron-deficient around Z = 82, e.g. 184Hg, 188Pb, 196Po stable nuclei observed nuclei unknown nuclei (predicted) 82 Pb 208 50 126 78 28 20 50 8 28 20 28 Ni 82 Ni Most exotic doubly-magic nucleus which can be investigated in foreseeable future 78
The SpecMAT project (ERC grant, R. Raabe) To investigate exotic nuclei, specifically neutron-rich around Z = 28, e.g. 68, 70Ni; 78, 80Zn (d,p); (d,3he) neutron-deficient around Z = 82, e.g. 184Hg, 188Pb, 196Po (d,p); (p,d) stable nuclei observed nuclei unknown nuclei (predicted) 82 Pb 208 50 126 78 28 20 50 8 28 20 28 Ni 82 Direct transfer reactions possible in this region with 5 10 MeV/u beams from HIE-ISOLDE at CERN
The SpecMAT project (ERC grant, R. Raabe) To investigate exotic nuclei, specifically neutron-rich around Z = 28, e.g. 68, 70Ni; 78, 80Zn (d,p); (d,3he) neutron-deficient around Z = 82, e.g. 184Hg, 188Pb, 196Po (d,p); (p,d) Active gas Target (ACTAR TPC) o Gas constitutes both target & detection medium o Optimal luminosity & resolution for particle detection Direct transfer reactions possible in this region with 5 10 MeV/u beams from HIE-ISOLDE at CERN
ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 16 384 channels in 2016 Each channel corresponds to one 2 mm * 2 mm pad => 256 mm * 256 mm segmented detection plane Will use the existing GET electronic system
ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 16 384 channels in 2016 Each channel corresponds to one 2 mm * 2 mm pad => 256 mm * 256 mm segmented detection plane Will use the existing GET electronic system ACTAR collaboration: France: Grand Accélérateur National d'ions Lourds (GANIL), Caen Institut de Physique Nucleaire (IPN) Orsay Centre Etudes Nucléaires de Bordeaux Gradignan (CENBG) Institut de recherche sur les lois fondamental de l'univers (IRFU) Saclay Universidade de Santiago de Compostela (Spain) Instituut voor Kern- en Stralingsfysica (IKS), KU Leuven (Belgium)
ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 16 384 channels in 2016 magnetic field Each channel corresponds to one 2 mm * 2 mm pad => 256 mm * 256 mm segmented detection plane Will use the existing GET electronic system With SpecMAT o Initial plan: magnetic field in direction parallel to beam particles to confine emitted particles. o Would use UK Solenoid at Daresbury (right), but this is not yet ready.. electric field
ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 16 384 channels in 2016 Each channel corresponds to one 2 mm * 2 mm pad => 256 mm * 256 mm segmented detection plane Will use the existing GET electronic system, as will ancillary detectors? Ancillary detectors: DSSSD array for charged-particle detection Gamma ray detectors SpecMAT
LaBr3:Ce scintillators Resolution 2.7-3.5% for 662 kev gamma rays from Cs Density 5.07 g/cm3 Internal contamination problems due to Lanthanum Patented by Saint Gobain (though also sold through Canberra, Ortec..) Price ~ 9 000 EUR per scintillator for 1.5"*1.5" model CeBr3 scintillators Resolution 3.8-4.3% for 662 kev gamma rays from Cs Density 5.19 g/cm3 No internal background (unless you have 227Ac contamination) Available from Scionix Holland, RMD.. Price ~ 4 500 EUR per scintillator for 1.5"*1.5" model
Looking into buying scintillators for testing, with dimensions: 1.5" 1.5" 2" 1.5" 2" 2" Optimal surface coverage with 2" diameter scintillators: 9 scintillators per side => 45 scintillators over 5 sides
ACTAR TPC: 256 mm * 256 mm = 65 536 mm2 per side 6 * 65 536 mm2 = 393 216 mm2 total surface area 9 51-mm-diameter scintillators per side 9 * 2043 mm2 = 18 387 mm2 per side 5 * 18 387 mm2 = 91 935 mm2 over 5 sides 28% coverage per side
ACTAR TPC: 256 mm * 256 mm = 65 536 mm2 per side 6 * 65 536 mm2 = 393 216 mm2 total surface area 9 51-mm-diameter scintillators per side 9 * 2043 mm2 = 18 387 mm2 per side 5 * 18 387 mm2 = 91 935 mm2 over 5 sides 23% coverage over ACTAR
Alternative solution: BEGe detectors from Canberra Diameter = 90 mm Thickness = 30 mm Figure from Canberra website: http://www.canberra.com/products/detectors
Alternative solution: BEGe detectors from Canberra Diameter = 90 mm Thickness = 30 mm 4 detectors of 6500 mm2 each per side. 4 * 6 500 mm2 = 26 000 mm2 coverage per side 3 * 26 000 mm2 = 78 000 mm2 total coverage on 3 sides ACTAR TPC: 256 mm * 256 mm = 65 536 mm2 per side 6 * 65 536 mm2 = 393 216 mm2 total surface area => 40% coverage per side
Alternative solution: BEGe detectors from Canberra Diameter = 90 mm Thickness = 30 mm 4 detectors of 6500 mm2 each per side. 4 * 6 500 mm2 = 26 000 mm2 coverage per side 3 * 26 000 mm2 = 78 000 mm2 total coverage on 3 sides ACTAR TPC: 256 mm * 256 mm = 65 536 mm2 per side 6 * 65 536 mm2 = 393 216 mm2 total surface area => 20% coverage over ACTAR
Geant4 simulations Scintillators Reaction Ni(d,p)79Ni, Pressure = 800 mbar 78 9 LaBr3:Ce or CeBr3 scintillators on each of 5 sides
Geant4 simulations Scintillators Reaction Ni(d,p)79Ni, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From 10 000 ACTAR events 2"*1.5 scintillators: 721 gamma rays observed 7.21% efficiency From 500 000 ACTAR events 2"*2 "scintillators: 40392 gamma rays observed 8.10% efficiency 12% gain in efficiency
Geant4 simulations Scintillators Reaction Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From 500 000 ACTAR events 28 339 gamma rays observed 5.67% efficiency (0-2 MeV) 40392 gamma rays 8.10% efficiency (0-5 MeV)
Geant4 simulations Scintillators Reaction Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From 500 000 ACTAR events 28 339 gamma rays observed 5.67% efficiency (0-2 MeV) 40392 gamma rays 8.10% efficiency (0-5 MeV)
Geant4 simulations Broad energy Ge detectors Reaction Ni(d,p)79Ni, Pressure = 800 mbar 78 4 BEGe detectors on each of 3 sides From 10 000 ACTAR events 334 gamma rays observed 3.34% efficiency
Prototypes to be tested with chamber at KU Leuven
Prototypes to be tested with chamber at KU Leuven Hence their flanges & O-ring grooves must fit to hole in this chamber.
Prototype scintillators to be tested with Osprey digital tube base (one purchased & received) Figure from Canberra website: http://www.canberra.com/products/detectors
Prototype scintillators to be tested with Analogue electronics Osprey digital tube base (one bought) Multichannel digitizer FEBEX system of GSI GET system already used for ACTAR demonstrator
Summary Simulations: CeBr3-8.09% efficiency with 45 2"*2" scintillators - 7.21% efficiency with 45 2"*1.5" scintillators LaBr3:Ce - 7.93% efficiency with 45 2"*2" scintillators - 6.87% efficiency with 45 2"*1.5" scintillators BEGe - 3.34% efficiency covering 3 sides (12 detectors) Prototypes to be tested: 1.5"*1.5" LaBr3:Ce detector 1.5"*1.5" CeBr detector 3 2"*2" CeBr3 detector Tests to be performed with various electronic systems 1st half of 2015 Complete design, start purchase by Christmas 2015
Hiring two PhD students for SpecMAT from September 2015. Contact raabe@kuleuven.be
Acknowledgement: The research leading to these results has received funding from the European Commission s Seventh Framework Programme (FP7/2007-2013) under the grant agreement SpecMAT (project no. 617156).
Go raibh maith agat Thank you for listening
Backup slides
Reaction 78Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 9 CeBr3 scintillators on each of 5 sides After 500 000 ACTAR events Backup slides
Geant4 simulations Scintillators Reaction Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From 500 000 ACTAR events 28 339 gamma rays observed 5.67% efficiency (0-2 MeV) Right: Data from R. Orlandi et al.