Current status of the analysis experiment e731

1. Current status of the analysis experiment e731 Universidade de São Paulo / Universitá degli Studi di Padova Rafael Escudeiro Orsay, June 24th – June 28th, 2019 Fourth Workshop of the Nuclear Spectroscopy Instrumentation Network NUSPIN 2019 and Annual Open Meeting of the AGATA Collaboration and Meetings of the NUSPIN Working Groups and Scientific Committee

2. Rafael Escudeiro Motivation Observation of excited states in 71Kr for the first time and study the Mirror Energy Differences (MED) in the pair 71Kr − 71Br; The MED have been extensively studied for pairs of mirror nuclei in the upper sd-shell and the lower fp-shell regions; Heaviest mirror nuclei with Tz = ± 1/2 in which MED will be experimentally measured; Allows to study isospin symmetry breaking effects;

3. Rafael Escudeiro General overview of the experiment AGATA + NEDA (+Neutron Wall) + DIAMANT 115 MeV of 36Ar into 40Ca target; About 60 runs with beam on the target with trigger set for gg, ggn; 1 reference run with no trigger in particles to estimate efficiency; Total statistics of the processed experiment: ~ 2 x 1010 J.J. Valiente-Dobón, G. Jaworski, A. Goasduff et al. Nuclear Inst. and Methods in Physics Research, A 927 (2019) 81–86

4. Rafael Escudeiro Initial treatment of data Raw data needs to be processed and merged in order to produce useful spectra. AGATA NEDA DIAMANT Data replay on the Post-PSA level Data replay Charge comparison parameters Data replay Charge comparison parameters Data replay Thresholds Merging Replayed data

5. Rafael Escudeiro NEDA NEDA is composed by liquid scintillator ELJEN EJ301; It makes the detectors sensitive to bothneutrons and gamma-ray radiation; Objective: Check the neutron selectivity and achieve a reasonable one; Neutron and gamma-rays produces different pulse shapes when interacts within the detector; Charge comparison utilizestwo integration gates, one for the fast part and anotherone for the slow part of thesignal; Gamma-rays Neutrons CC J.J. Valiente-Dobón, G. Jaworski, A. Goasduff et al. Nuclear Inst. and Methods in Physics Research, A 927 (2019) 81–86 Pulse Shape Analysis of the NEDA Detector A. Raggio, G. Jaworski, V. Modamio, J.J. Valiente-Dobon, A. Goasduff , B. Saygı˘. LNL annual report.

6. Rafael Escudeiro NEDA – Neutron CC selectivity Objective: Check the neutron selectivity and achieve a reasonable one; Time of flight and energy are also different between neutrons and gamma-rays; Combining CC with time of flight and/or energy, it is possible to achieve a good separation for neutrons; Time of Flight Energy ToF(ns) Energy (ch)

7. Rafael Escudeiro NEDA – Neutron CC selectivity Objective: Check the neutron selectivity and achieve a reasonable one; 1 detector example

8. Rafael Escudeiro NEDA – Neutron CC selectivity Objective: Check the neutron selectivity and achieve a reasonable one; 1 detector example

9. Rafael Escudeiro DIAMANT DIAMANT, light-charged particle detector composed by 56 pieces of CsI(Tl); Analogue double integral gates for the signal, produces the particle identification; 1 detector example; proton alpha

10. Rafael Escudeiro AGATA AGATA replays can be performed at tree different levels: pre-PSA, PSA and Post PSA; For this experiment only some calibrations runs stored traces that allows all levels of the replays to be processed; All remaining the PSA was stored allowing only the Post-PSA level to be done; A crucial step is to merge the AGATA and ancillaries detectors data; Only a nice view of the crystals;

11. Rafael Escudeiro Time differences within a given window, to merge

12. Rafael Escudeiro Reference run for estimating efficiency As said before, the reference run can be used to estimated an efficiency; No particle gate Alpha gate Proton gate Neutron gate

13. Rafael Escudeiro Neutron detection efficiency 10³ 1 n gated spectrum Unrestricted spectrum Gamma-ray events taken in a particular transition; The number of events between was then compared between the unrestricted and the neutron gated ones; 49Cr transitions Achieved efficiency:~15% Achieved efficiency:~12% Similar results were find across neutron related transitions.

14. Rafael Escudeiro Gamma-rays misidentified as neutrons Selecting a no-neutron related gamma-ray transition; Comparing the number of events in the unrestricted and in neutron related channels; Events in the unrestricted spectrum: 523540 Events in the 1n gated spectrum: 369 Unrestricted 1n gated Leaking = ~ 0.070%

15. Rafael Escudeiro Alpha particles detection efficiency Unrestricted Alpha gated Gamma-ray events taken in a particular transition; The number of events between was then compared between the unrestricted and the alpha gated one; 47V (1a1p) transitions Achieved efficiency:~31% Similar results were find across alpha related transitions.

16. Rafael Escudeiro Proton particles detection efficiency Gamma-ray events taken in a particular transition; The number of events between was then compared between the unrestricted and the proton gated one; Proton gated 50Mn (1n1p) transition Achieved efficiency:~36% Similar results were find across proton related transitions.

17. Rafael Escudeiro Proton misidentified as alpha particles An analogue procedure for DIAMANT particle miss identification; Known 2pn transition leaking into alpha channel; Events in the unrestricted spectrum: 543756 Events in the 1a gated spectrum: 472 Unrestricted Alpha Leaking = ~ 0.087%

18. Rafael Escudeiro Gamma-rays energy spectrum

19. Rafael Escudeiro Gamma-rays energy spectrum In our experiment, the target was contaminated with oxygen. 1a1p 88 keV 47V transitions observed 46Ti 1a2p contaminant 46V 1a1p1n contaminant 1149 keV 146 keV 1320 keV 547 keV 1087 keV 1518 keV

20. Rafael Escudeiro Gamma-rays energy spectrum In our experiment, the target was contaminated with oxygen. 1a1n 98 keV 47Cr transitions observed 49Cr 2p1n contaminant 75 keV 46V 1a1p1n contaminant 1158 keV 1321 keV 547 keV 1486 keV 1248 keV

21. Rafael Escudeiro Gamma-rays energy spectrum Target was contaminated with oxygen. For this reason, the most populated channels was with oxygen; Only the strongest channels of the reaction with 40Ca was possible to identify, so far: 70Se ( 2p1a ); 73Kr ( 2p1n ); 73Kr 70Se 611 keV 944 keV 655 keV 1094 keV

22. Rafael Escudeiro Summary The ancillary detector data was processed and efficiency found were: NEDA 15% efficiency was achieved with a 0.070% leaking DIAMANT 31% efficiency for alphas 36% efficiency for protons The total statistics of the experiment was processed and the reaction with oxygen has a strong presence in the spectra; Next steps: Checking the neutron energy threshold in NEDA; Checking neutron damage correction; Checking the possible nuclei to study from the reactions with calcium and oxygen;

23. Rafael Escudeiro Thank you very much Obrigado Grazie