1. Coulomb excitation of the 42Ca with AGATA Demonstrator
K. Hadyńska-Klęk1,2
P.J. Napiorkowski1, A. Maj3, F. Azaiez4, J.J. Valiente Dobon5
on behalf of the AGATA Collaboration
1) Heavy Ion Laboratory, University of Warsaw, Warsaw, Poland
2) Institute of Experimental Physics, University of Warsaw, Warsaw, Poland
3) H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland
4) Institute for Nuclear Physics, Orsay, France
5) INFN Laboratori Nazionali di Legnaro, Legnaro, Italy 1

2. 40Ca vs 42Ca
Highly collective structure were found in the 40Ca (also in 36,38Ar)
B(E2; 4+ 2+ in SD) = 170 W.u (DSAM)
Deformation of the 2+ state in the superdeformed band: β2=0.59(9)
(E. Ideguchi et al.,
Phys. Rev. Lett )
42Ca Ca 2 2 2 2 2

3. 40Ca vs 42Ca
B(E2) values in 42Ca suggest smaller deformation of the of the 0+(1837 keV) band than in the case of 40Ca
observation of GDR feeding of presumably deformed band in 42Ca from very deformed hot 46Ti
(M.Kmiecik et al. Acta Phys. Pol. B36, 1169(2005))
moment of inertia very similar to that found for the SD-band in 40Ca
42Ca 3 3 3

4. 42Ca LNL
DANTE: 3 MCP detectors
covered θ range 100°-144°
beamtime: Feb.2010
beam: 42Ca, 170 MeV
target: 208Pb, 1 mg/cm2
AGATA: 3 clusters
at mm from the target
particle – γ coincidence mode: trigger rate 150÷250 Hz 4 4 4 4 4

5. Preliminary results K. Hadyńska-Klęk et al.,
(Acta Phys. Pol B 42, 817 (2011)) 5

6. Preliminary results K. Hadyńska-Klęk et al.,
(Acta Phys. Pol B 42, 817 (2011)) 6

7. Doppler Effect Correction
42Ca
208Pb
42Ca

8. Doppler Effect Correction
208Pb
42Ca
208Pb
42Ca

9.  lines after Doppler correction – two MCP detectors at θ1=210o and θ2=150o9

10. Tentative level scheme of 42Ca
K. Hadyńska-Klęk et al.,
(Acta Phys. Pol B 42, 817 (2011)) 10

11. If 1- at 3885 keV… E1 E3 Excitation via E2(01+ → 21+) and
E3(21+→ 1-) transitions
Deexcitation via E1(1- → 02+ ) 2048 keV
GOSIA calculations:
B(E3; 21+→ 1-) > 2.5*106 W.u. E2 11

12. If 1- at 3885 keV… EXCLUDED E1 E3 Excitation via E2(01+ → 21+) and
E3(21+→ 1-) transitions
Deexcitation via E1(1- → 02+ ) 2048 keV
GOSIA calculations:
B(E3; 21+→ 1-) > 2.5*106 W.u. E2 12

13. Postulated interpretation
We assume that the observed gamma line comes from a 2+ level placed at 2048 keV
The 22+ state can be populated directly via
E2(01+ → 22+)
Deexcitation – through E2(22+ → 01+) with 2048 keV
It was enough to reproduce the intensity of the
2048 keV gamma ray with B(E2; 22+ → 01+) ~ 1 W.u
Observation of the 376 keV line supports this scenario
But...
No signs of this lines in the known level scheme and previous experiments
W.J. Kossler et al., Phys. Rev. 177, 1725 (1969) 13 13 13

14. Another unexpected 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!
1729 keV = 4400 counts
2424 keV = 300 counts
It seems that the 42+ state is populated stronger that the 22+ in the same band!
Excitation of the presumably SD band is smaller then it was expected or…
Deexcitation of 2424 keV state goes also through the 376 keV! 14

15. Motivation for the additional experiments
- coincidences analysis was performed but is not conclusive
As long as 376 and 2048 keV  lines are not placed in the level scheme, the COULEX analysis results will require to make additional assumptions
Also proovement of the possible superdeformation will be less convincing
The aim of the additional experiments: investigation of the medium and low spin region in 42Ca 15

16. Experiment @ HIL Warsaw
Beam: 32S, 1 pnA, 76 MeV
Target: 12C, 4 mg/cm2
Reaction: 12C(32S,2p)42Ca
Cross section for 2p reaction channel:
110 mb (COMPA & PACE codes)
EAGLE-II array
The most important issues:
- possible new level at 2048 keV
- branching ratio determination of the decay  lines from 2424 keV level
-  ray angular correlation – to assign spin and parity of the new state(s) 16

17. Experiment @ HIL Warsaw
Beam: 32S, 1 pnA, 76 MeV
Target: 12C, 4 mg/cm2
Reaction: 12C(32S,2p)42Ca
Cross section for 2p reaction channel:
110 mb (COMPA & PACE codes)
EAGLE-II array
ACCEPTED
10-14.X.2011
The most important issues:
- possible new level at 2048 keV
- branching ratio determination of the decay  lines from 2424 keV level
-  ray angular correlation – to assign spin and parity of the new state(s) 17

18. Any theories?

19. Any theories? If yes, please contact me: kasiah(at)slcj.uw.edu.pl

20. Special thanks to
P.J. Napiorkowskia, A. Majb, F. Azaiezc, J.J. Valiente-Dobond, G. de Angelisd, Anil Kumarb, D. Bazzaccoe, P. Bednarczykb, M. Bellatoe, G. Benzonif, L. Bertid, D. Bortolatod, B. Bruyneelg, F. Cameraf, M. Ciemałab, P. Cocconid, A. Colomboe, A. Corsif,F. Crespif, A. Czermakb, Ch. Drostei, B. Dulnyb, E. Farneae, B. Fornalb, S. Franchooc, A. Gadeah, A. Giazf, A. Gottardod, X. Gravec, J. Gręboszb, E. Grodneri, M. Gulminid, H. Hessg, R. Isocratee, J.Iwanickia, G. Jaworskia,l, M. Kicińska-Habiori, M. Kmiecikb, N. Kondratyevj, A. Korichim, W. Kortenn, J. Kownackia, M. Kowalczyka, M.Kisielińskia, G. Lehauto, S. Lenzie,k, S. Leonif, S. Lunardie,k, G. Marond, R. Menegazzoe, D. Mengonip,e, E. Merchanr,s, W. Męczyńskib, C. Michelagnolie,k, J. Mierzejewskia, P. Molinie,k, D.R. Napolid, R. Nicolinif, M. Niikurac, M. Palacza, G. Rampazzoe, F. Recchiae,k, N. Redono, P. Reiterg, D. Rossod, E. Sahind, J. Srebrnya, I. Stefanc, O. Stezowskio, J. Styczeńb, N. Toniolod, C.A. Ure, V. Vandonef, B. Wadswortht, A. Wiensg, K. Wrzosek-Lipskaa, M. Zielińskaa, M. Zięblińskib
a) Heavy Ion Laboratory, University of Warsaw, Warsaw, Poland b) H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Kraków, Poland c) Institute of Nuclear Physics, Orsay, France d) INFN Laboratori Nazionali di Legnaro, Legnaro, Italy e) INFN Sezione di Padova, Padova, Italy f) Universita di Milano and INFN sezione di Milano, Milano, Italy g) University of Cologne, Cologne, Germany h) IFIC, CSIC-University of Valencia, Valencia, Spain i) Institute of Experimental Physics, University of Warsaw, Warsaw, Poland j) Joint Institute for Nuclear Research, Dubna, Russia k) Universita' di Padova, Padova, Italy l) Faculty of Physics, Warsaw University of Technology, Warsaw, Poland m) CSNSM Orsay, France n) CEA Saclay, France o) IPN Lyon, France p) University of the West of Scotland, Paisley, UK r) TU Darmstadt, Germany s) GSI Darmstadt, Germany t) University of York, York, UK 20