UNIVERSITY OF JYVÄSKYLÄ Results from the first tests with the SPEDE spectrometer Philippos Papadakis ISOLDE Workshop and Users Meeting 2014

UNIVERSITY OF JYVÄSKYLÄ Motivation Shape coexistence: A. Andreyev et al., Nature (London) 405, 430 (2000). Octupole collectivity: L.P. Gaffney et al., Nature (London) 497, 199 (2013). 186 Pb

UNIVERSITY OF JYVÄSKYLÄ Approved proposals Proposals –P. Butler, D.T. Joss, M. Scheck et al., IS552 - Measurements of octupole collectivity in Rn and Ra nuclei using Coulomb excitation –J. Pakarinen et al., IS556 - Probing intruder configurations in 186,188 Pb using Coulomb excitation –K. Wrzosek-Lipska, D.T. Joss, D. Jenkins, J. Pakarinen et al., IS563 - Coulomb excitation of Hg: Shape coexistence in the neutron-deficient lead region –P.A. Butler, D.T. Joss et al., IS475 - Measurements of octupole collectivity in odd-mass Rn and Ra nuclei using Coulomb excitation LOIs: –P. Butler et al., Measurements of octupole collectivity in odd-mass Rn, Fr and Ra isotopes –N. Warr et al., Shape studies in the neutron rich N ~ 60 region –P. Van Duppen D.T. Joss, D.G. Jenkins, J. Pakarinen et al., Shape coexistence in the neutron-deficient region around Z=82 studied via Coulomb excitation and few-nucleon transfer reactions –D. Jenkins et al., Shape changes and proton-neutron pairing around the N=Z line

UNIVERSITY OF JYVÄSKYLÄ Miniball array CD detector Target e-e- γ-ray SPEDE concept Silicon detector Beam

UNIVERSITY OF JYVÄSKYLÄ From concept to design Si-detector Absorber foil Target CD-detector

UNIVERSITY OF JYVÄSKYLÄ From design to reality

UNIVERSITY OF JYVÄSKYLÄ SPEDE in Miniball

UNIVERSITY OF JYVÄSKYLÄ δ electron suppression Low energy electrons produced when beam and target particles collide Detector at backwards angle HV on target Absorber foil between target and detector RIBs - Lower beam intensity β-decay background supressed through coincidences with scattered particles U. Bechthold et al., Phys. Rev. Lett 79, 2034 (1997)

UNIVERSITY OF JYVÄSKYLÄ Absorber foil Covers detector surface Hole for the beam Different materials and thicknesses tested (Aluminium, Aluminised Mylar, Mylar). Al 30μm Al Mylar 12μm Al 30μm Al Mylar 12μm ~10keV 320keV~7.5keV 320keV~6keV 320keV No foil Energy loss of electrons through Al foil Energy loss of electrons through Al Mylar foil

UNIVERSITY OF JYVÄSKYLÄ Biased target Bias on in-beam target up to 5kV Other targets floating or at ground potential

UNIVERSITY OF JYVÄSKYLÄ Detector design 24 segments 48 segments 24 segments 48 segments Geant4 simulation Beam: MeV/u, Target: 112 Cd, 2 mg/cm 2 J. Konki et al., EPJ Web of Conferences 63, (2013).

UNIVERSITY OF JYVÄSKYLÄ Detector design – simulated efficiency Courtesy of D. Cox.

UNIVERSITY OF JYVÄSKYLÄ Silicon detector and PCB layout 24 segments, 500μm thick. Copper cooling block Cooled to -15C

UNIVERSITY OF JYVÄSKYLÄ In-beam tests Investigate: –If the concept works –Performance of SPEDE –δ-electron suppression Cocktail beam: 20 Ne, 40 Ar, and 60 Ni Beam intensity and time profile similar to HIE-ISOLDE 100μs 1ms or 10ms Beam intensity up to 50E6pps: Count rate per channel ~20kHz

UNIVERSITY OF JYVÄSKYLÄ In-beam tests

UNIVERSITY OF JYVÄSKYLÄ 174 Yb Coulex test 40 Ar on 174 Yb E beam 4.1MeV/u, I beam ~40E6pps Aluminised Mylar foil Tests with no high-voltage and 5kV on target 174 Yb Conversion electrons for the 176.7keV transition: K: 115.3keV L: 166.1keV

UNIVERSITY OF JYVÄSKYLÄ High-voltage On/Off

UNIVERSITY OF JYVÄSKYLÄ X ray and δ electron pile-up signal

UNIVERSITY OF JYVÄSKYLÄ Commissioning – 197 Au at 4.1 MeV/u on 112 Cd Coulex experiment –Well known level scheme –Highly converted transitions –Reaction kinematics close to our MINIBALL Coulex programme 197 Au

UNIVERSITY OF JYVÄSKYLÄ Project time line Mechanical design Electronic tests Proposals to INTC Development at JYFL In-beam tests at JYFL Commissioning at JYFL HIE-ISOLDE stage 1 SPEDE campaign 

UNIVERSITY OF JYVÄSKYLÄ Summary Possibility to measure γ-rays and conversion electrons simultaneously HIE-ISOLDE First in-beam JYFL completed  Concept works More in-beam tests and JYFL in 2015 Ready for in-beam use at HIE-ISOLDE second half of 2015 For more information: – / –P. Papadakis et al., JPS Conference Proceedings, article in press (An introduction to SPEDE) –J. Konki et al., EPJ Web of Conferences 63, (2013) (Simulations)

UNIVERSITY OF JYVÄSKYLÄ Collaboration University of Jyva ̈ skyla ̈, Finland J. Pakarinen, P. Papadakis, P.T. Greenlees, J. Konki, P. Rahkila, K. Ranttila, V.P. Saarela University of Liverpool, United Kingdom P.A. Butler, D.M. Cox, R.-D. Herzberg, G.G. O’Neill, J. Thornhill, D. Wells University of York, United Kingdom P. Davies, D.G. Jenkins Katholieke Universiteit Leuven, Belgium M. Huyse, P. Van Duppen