The SpecMAT Project: An array of gamma ray detectors around an active target

Transcription

1 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

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5 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 Ni 82

6 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 Ni 82 Ni Most exotic doubly-magic nucleus which can be investigated in foreseeable future 78

7 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 Ni 82 Direct transfer reactions possible in this region with 5 10 MeV/u beams from HIE-ISOLDE at CERN

8 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

9 ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 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

10 ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 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)

11 ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 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

12 ACTAR-TPC (ERC grant, G.F. Grinyer) Based at GANIL, to be used at HIE-ISOLDE Demonstrator (2048 channels) operational Final detector: 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

13 LaBr3:Ce scintillators Resolution % 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 ~ EUR per scintillator for 1.5"*1.5" model CeBr3 scintillators Resolution % 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 ~ EUR per scintillator for 1.5"*1.5" model

14 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

15 ACTAR TPC: 256 mm * 256 mm = mm2 per side 6 * mm2 = mm2 total surface area 9 51-mm-diameter scintillators per side 9 * 2043 mm2 = mm2 per side 5 * mm2 = mm2 over 5 sides 28% coverage per side

16 ACTAR TPC: 256 mm * 256 mm = mm2 per side 6 * mm2 = mm2 total surface area 9 51-mm-diameter scintillators per side 9 * 2043 mm2 = mm2 per side 5 * mm2 = mm2 over 5 sides 23% coverage over ACTAR

17 Alternative solution: BEGe detectors from Canberra Diameter = 90 mm Thickness = 30 mm Figure from Canberra website:

18 Alternative solution: BEGe detectors from Canberra Diameter = 90 mm Thickness = 30 mm 4 detectors of 6500 mm2 each per side. 4 * mm2 = mm2 coverage per side 3 * mm2 = mm2 total coverage on 3 sides ACTAR TPC: 256 mm * 256 mm = mm2 per side 6 * mm2 = mm2 total surface area => 40% coverage per side

19 Alternative solution: BEGe detectors from Canberra Diameter = 90 mm Thickness = 30 mm 4 detectors of 6500 mm2 each per side. 4 * mm2 = mm2 coverage per side 3 * mm2 = mm2 total coverage on 3 sides ACTAR TPC: 256 mm * 256 mm = mm2 per side 6 * mm2 = mm2 total surface area => 20% coverage over ACTAR

20 Geant4 simulations Scintillators Reaction Ni(d,p)79Ni, Pressure = 800 mbar 78 9 LaBr3:Ce or CeBr3 scintillators on each of 5 sides

21 Geant4 simulations Scintillators Reaction Ni(d,p)79Ni, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From ACTAR events 2"*1.5 scintillators: 721 gamma rays observed 7.21% efficiency From ACTAR events 2"*2 "scintillators: gamma rays observed 8.10% efficiency 12% gain in efficiency

22 Geant4 simulations Scintillators Reaction Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From ACTAR events gamma rays observed 5.67% efficiency (0-2 MeV) gamma rays 8.10% efficiency (0-5 MeV)

23 Geant4 simulations Scintillators Reaction Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From ACTAR events gamma rays observed 5.67% efficiency (0-2 MeV) gamma rays 8.10% efficiency (0-5 MeV)

24 Geant4 simulations Broad energy Ge detectors Reaction Ni(d,p)79Ni, Pressure = 800 mbar 78 4 BEGe detectors on each of 3 sides From ACTAR events 334 gamma rays observed 3.34% efficiency

25 Prototypes to be tested with chamber at KU Leuven

26 Prototypes to be tested with chamber at KU Leuven Hence their flanges & O-ring grooves must fit to hole in this chamber.

27 Prototype scintillators to be tested with Osprey digital tube base (one purchased & received) Figure from Canberra website:

28 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

29 Summary Simulations: CeBr3-8.09% efficiency with 45 2"*2" scintillators % efficiency with 45 2"*1.5" scintillators LaBr3:Ce % efficiency with 45 2"*2" scintillators % efficiency with 45 2"*1.5" scintillators BEGe % 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

30 Hiring two PhD students for SpecMAT from September Contact

31 Acknowledgement: The research leading to these results has received funding from the European Commission s Seventh Framework Programme (FP7/ ) under the grant agreement SpecMAT (project no ).

32 Go raibh maith agat Thank you for listening

33 Backup slides

34 Reaction 78Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 9 CeBr3 scintillators on each of 5 sides After ACTAR events Backup slides

35 Geant4 simulations Scintillators Reaction Ni(d,p)79Ni at 780 MeV, Pressure = 800 mbar 78 9 CeBr3 scintillators on each of 5 sides From ACTAR events gamma rays observed 5.67% efficiency (0-2 MeV) Right: Data from R. Orlandi et al.