Coulomb excitation of the presumably super-deformed band in 42 Ca - preliminary results from the first AGATA Demonstrator experiment Katarzyna Hadyńska-Klęk 1 F. Azaiez 3, A. Maj 2, P. Napiorkowski 1 and the AGATA collaboration* * Univ. Ankara, Turkey; Univ. Bonn, Germany; NIPNE Bucharest, Romania; Univ. Brighton, UK; GANIL, Caen, France; Univ. Camerino, Italy; NBI Copenhagen, Danmark; Univ. Cracow, Poland; STFC Daresbury, UK; GSI Darmstadt, Germany; TU Darmstadt, Germany; INFN Firenze, Italy; INFN Genova, Italy; Univ. Göteborg, Sweden; FZ Jülich, Germany; Univ. Jyväskylä, Finland; Univ. Keele, UK; Univ. Köln, Germany; IFJ PAN Krakow, Poland; INFN Legnaro, Italy; Univ. Liverpool, UK; Univ. Istanbul, Turkey; IPN Lyon, France; Univ. Lund, Sweden; Univ. Manchester, UK; INFN/Univ. Milano, Italy; LMU München, Germany; TU München, Germany; INFN Napoli, Italy; CSNSM Orsay, France; IPN Orsay, France; INFN/Univ. Padova, Italy; Univ. Paisley, UK; INFN Perugia, Italy; CEA Saclay, France, Dapnia; Univ. Sofia, Bulgaria; KTH Stockholm, Sweden; IPHC Strasbourg, France; Univ. Surrey, UK; IPJ Swierk, Poland; Univ. of Warsaw, Poland; Univ. Uppsala, Sweden; Univ. York, UK 17 th Nuclear Physics Workshop "Marie & Pierre Curie” Kazimierz 2010

Motivation - 40 Ca Highly colective structure found in 40 Ca B(E2; 4 + → 2 + in SD) = 170 W.u (DSAM) || Deformation of the 2 + state in the superdeformed band: β 2 =0.59(9) ( E. Ideguchi et al., Phys. Rev. Lett )

42 Ca 40 Ca

Highly collective structure were found in the A~40 region ( 40 Ca, 36,38 Ar) B(E2) values in 42 Ca suggest smaller deformation of the of the 0 + (1837 keV) band than in the case of 40 Ca observation of GDR feeding of presumably deformed band in 42 Ca from very deformed hot 46 Ti (M.Kmiecik et al. Acta Phys. Pol. B36, 1169(2005)) - (SD bands preferential feeding by the low energy component of the highly split GDR decaying?) moment of inertia very similar to that found for the SD-band in 40 Ca 40 Ca vs 42 Ca 42 Ca

First experiment with AGATA LNL Legnaro AIMS OF THE EXPERIMENT: to proof the possibility of Coulomb excitation of highly deformed bands in A~40 region nuclei, to determine the B(E2) values for low spin part of the presumable super- deformed band in 42 Ca, to expand the knowledge about the electromagnetic properties of low- laying states in 42 Ca, to determine quadrupole moments for the both ground state and SD bands. IN ADDITION the response of the AGATA Demonstrator for low multiplicity gamma rays in a wide energy range 300 – 2500 keV, the coincidence mode of DAQ with particle detector connected via AGAVA interface the Doppler correction of a detected gamma rays in quasielastic kinematic.

First physical experiment with AGATA LNL Legnaro beamtime: beam: 42 Ca, 170 MeV targets: 208 Pb, 1 mg/cm 2, 197 Au, 1 mg/cm 2 (tests + setting up) DANTE: 3 MCP detectors covered θ range 100°-144° AGATA: 3 clusters at mm from the target particle – γ coincidence mode: trigger rate 150÷250 Hz

Observed decay scheme of 42 Ca E [keV]

Possible scenario #1 Excitation via E2(0 1 + → ) and E3(2 1 + → 1 - ) transitions Deexcitation via E1(1 - → ) 2048 keV GOSIA calculations: B(E3; → 1 - ) > 2.5*10 6 W.u. This scenario has to be excluded E2 E3 E1

Possible scenario #2 We assume that the observed gamma line comes from a 2 + level placed at 2048 keV. The state can be populated directly via E2(0 1 + → ) Deexcitation – through E2(2 2 + → ) 2048 keV It was enough to reproduce the intensity of the 2048 keV gamma ray with B(E2; → ) ~ 1 W.u only

Another surprising effect In multi-step Coulex each additional step leads to a weaker excitation → we expected more counts in the 2424 keV line than in the 1729 keV transition In the experiment, the 1729 keV line is stronger! Expected ratio: 1729 keV : 2424 keV = 1 : 2 Obtained ratio: 1729 keV : 2424 keV = 44 : 3 ! It seems that the state is populated stronger that the in the same band Excitation of the presumably SD band is smaller then it was expected from calculations

Summary Preliminary results from the Coulomb excitation of the 42 Ca - first physical experiment using AGATA Demonstrator Coulomb excitation of the levels up to 4 + states in the GS band and presumably SD band in 42 Ca was observed A very strong 2048 keV transition was observed → probably another 2 + state found

Special thanks to: D. Bazzacco 4, E. Farnea 4, G. de Angelis 4, D. Bartolato 4, P.Bednarczyk 2, M.Bellato 4, G. Benzoni 6, L. Berti 6, B. Bruyneel 10, F. Camera 6, M.Ciemała 2, P.Cocconi 4, A. Colombo 4, A. Corsi 6, F. Crespi 6, A. Czermak 2, B.Dulny 2, B.Fornal 2, S. Franchoo 3, A. Gadea 4, A. Gottardo 4, A.K. Gourishetty 2, X. Grave 3, J. Grębosz 2, M. Gulmini 6, R. Isocrate 4, G. Jaworski 1, M.Kicinska-Habior 1, M. Kmiecik 2, N. Kondratyev 4, A. Korichi 5, W.Korten 8, G. Lehaut 7, S. Lenzi 4, S.Leoni 6, S. Lunardi 4, G. Maron 6, R.Menegazzo 4, D.Mengoni 4, E. Merchan 11, W. Męczyński 2, C. Miechelagnoli 4, P. Molini 4, D.Napoli 4, R. Nicolini 6, M. Niikura 3, M. Palacz 1, G.Rampazzo 4, F. Recchia 4, N. Redon 7, P. Reiter 10, D. Rosso 4, E. Sahin 4, J.Srebrny 1, I. Stefan 3, O.Stezowski 7, J. Styczeń 2, N. Toniolo 4, C.A. Ur 4, V.Vandone 6, B.Wadsworth 9, A. Wiens 10, K. Wrzosek-Lipska 1, M. Zielińska 1, M.Ziębliński 2 1 University of Warsaw, Poland; 2 IFJ PAN Kraków, Poland; 3 IPN Orsay, France; 4 INFN, Legnaro and University of Padova, Italy; 5 CSNSM Orsay France; 6 Universita’ di Milano and INFN sezione di Milano, Italia; 7 IPN Lyon, France; 8 CEA Saclay, France; 9 University of York, UK; 10 University of Cologne, Germany 11 GSI Darmstadt, Germany

Towsley, Cline,

Pulse Shape Analysis to decompose recorded waves Highly segmented HPGe detectors · · Reconstruction of tracks evaluating permutations of interaction points Digital electronics to record and process segment signals Reconstructed gamma-rays AGATA - Ingredients of Gamma–Ray Tracking

Gamma energy without Doppler correction Gamma energy Doppler corrected 5%2% First gamma spectrum