ROGER CABALLERO FOLCH, Barcelona, 9 th November 2011

Introduction: Theoretical concepts Experiment proposal GSI facility and experimental setup Preliminary analysis Contents 2/16 GSI facility & setupPreliminary analysis IntroductionProposal

3/16 UPC Neutron detector (Beta delayed neutron, BELEN) GSI facility & setupPreliminary analysis IntroductionProposal Introduction Neutron detector designed and constructed by UPC GRETER research group. The detection of the neutron is based on the detection of products of the following reaction of the neutron with 3He counters Ion beam n n n Polyethylene moderator Proportional 3 He counter Silicon β decay detector 3 He + n → 3 H + 1 H keV Spectra obtained for each 3 He counter Edge effect 191 keV Full energy deposited 765 keV Noise

4/16 Neutron emission after β - decay scheme GSI facility & setupPreliminary analysis IntroductionProposal Introduction To measure neutron emission probabilities after beta decay of neutron rich isotopes with relevance in basic nuclear physics, astrophysics and nuclear technology.

5/16 neutron BETA Example of β - delayed neutron emission GSI facility & setupPreliminary analysis IntroductionProposal Introduction

6/16 Nuclear structure knowledge: study different aspects of the decay of these nuclei. Half lives and neutron emission probabilities provide information about their decay mechanism and structure. Relevance Astrophysics (r-process): β - decay studies near the r- process path. Pn values, together with decay half lives, are the main ingredients for the study of heavy elements nucleosynthesis via the r- process. The exact place for the r-process has not been identified yet. GSI facility & setupPreliminary analysis IntroductionProposal Introduction

S410: “Beta-decay measurements of new isotopes near the third r-process peak” 7/16 Has been performed at GSI in September 2011 with a week beam time. To measure half lives and beta delayed neutron emission probability of isotopes near the third abundance peak of the r-process (N≈126). The measurements were centered on isotopes 215 Tl, 211 Hg. Some isotopes around have already been identified. We expect to identify Hg Au 208,209 Pt 205,206 Ir Experiment objectives GSI facility & setupPreliminary analysis IntroductionProposal Introduction Tl

8/16 GSI facility & setupPreliminary analysis IntroductionProposal Status of the art N=126 t 1/2 existsidentified Area of interest P n (%) QRPA B n = 2-3 MeV Centered

9/16 GSI facility & setupPreliminary analysis IntroductionProposal Explosive nucleosynthesis and the r-process around the third abundance peak Effect of half-lives The Astr. Jour., 579 (2002), H. Schatz et al. Proc. CGS-13 (2009), G. Martinez-Pinedo “Ignorance”-Curve Focus of present proposal r-path

10/16 Difficult to calculate/predict half-live and Pn-values of the nuclei in this region: (I.Borzov, et al. 2003) FRDM + QRPA K.-L. Kratz, (private communication) T. Kurtukian-Nieto, et al., Phys. Lett. B (Submitted) K.-L. Kratz, (private communication) DF3 + QRPA + FRDM + QRPA Exp. T. Kurtukian et al. (P.Moeller, et al. 2003) GSI facility & setupPreliminary analysis IntroductionProposal

GSI facility. Fragment separator spectrometer (FRS) 11/16 GSI facility & setupPreliminary analysis IntroductionProposal GSI facility & setup Beam characteristics 238 U beam 1GeV/n 2x10 9 ions/s intensity 1.6 g/cm 2 Be target Proposal

S410 experiment setup 12/16 Neutron detector SIMBA Polyethylene shielding GSI facility & setupPreliminary analysis IntroductionProposal GSI facility & setup

S410 experiment setup 12/16 GSI facility & setupPreliminary analysis IntroductionProposal GSI facility & setup BELEN neutron detector Neutron shielding FRS detectors

SIMBA detector Silicon Implantation Detector and Beta Absorber (SIMBA) Multilayer silicon detector It allowed us to measure both ion implants and β-decays. Decay events can be correlated in time with the detection of neutrons. 13/16 GSI facility & setupPreliminary analysis IntroductionProposal GSI facility & setup Tracking layers XY (60 segm.) 60x60 mm 2 (0.3mm thick) 2 SSSD (7 segm.) 60x40 mm2 (1mm thick) 3 DSSD (implantation area, 60x40 segm.): 60x40 mm 2 (0.7mm thick) 2 SSSD (7 segm.) 60x40 mm 2 (1mm thick)

Neutron detector for FRS-GSI S410 experiment 30 3 He counters: · 20 with 20 atm pressure · 10 with 10 atm pressure 14/16 GSI facility & setupPreliminary analysis IntroductionProposal GSI facility & setup

15/16 Data analysis method based in Go4 & root GSI facility & setupPreliminar analysis IntroductionProposal Identification plot Tracking signals FRS detectors A/Q Z Bi Po Pb Tl Hg Preliminary analysis GSI facility & setup

15/16 Data analysis method based in Go4 & root GSI facility & setupPreliminary analysis IntroductionProposal Preliminary analysis A/Q Z 205Bi Calibration files for Z and AoQ (ID): 205 Bi & 216 Po keV Counts Gamma rays of Isomers

16/16 Data analysis method based in Go4 & root GSI facility & setupPreliminar analysis IntroductionProposal Preliminary analysis Location on silicon layer detector (SIMBA) Implantation Counts Energy deposited (ch) Noise Beta decay

16/16 Data analysis method based in Go4 & root GSI facility & setupPreliminar analysis IntroductionProposal Preliminary analysis β-β- β-β- n n keV Ch Beta disintegrations Implants β - decays c alibrations will be performed with a 137 Cs source β - decay curves will provide half lives values 252 Cf for BELEN efficiency Pulser Noise Neutron signal Counts Energy (ch)

The end! GRETER research group - Nuclear Engineering Section (SEN) Thanks to the fellowship of the Càtedra ARGOS www-w2k.gsi.de/frs-setup