Ideas for fast-timing experiments from TU Darmstadt … and recent results and technical developments Thorsten Kröll (TU Darmstadt) Work supported by BMBF (06DA02NUP and 05P12RDFN8) and LOEWE / HIC for FAIR - Recent results from EXILL&FATIMA - Embryonic ideas for new experiments - Digital fast-timing - LaBr 3 crystal from Kinheng

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 2 FATIMA & EXILL - recent results Neutron-rich Xe isotopes 138,140,142 Xe 139,141 Xe Stoyanka Ilieva Michael Habib 235 U(n,f) 242 Pu(n,f)

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 3 FATIMA & EXILL - recent results

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 4 FATIMA & EXILL - recent results

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 5 FATIMA & EXILL - recent results 2 +, 140 Xe  = 102(7) ps from 235 U data set  = 99(18) ps from 241 Pu data set  = 101.7(32) ps Lindroth, PRL 82, 4783 (1999) PRD Compton background Generalized Centroid Difference Method J.-M. Régis NIM A 726, 191 (2013)

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 6 FATIMA & EXILL - recent results 76 keV 112 keV

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 7 FATIMA & EXILL - recent results

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 8 FATIMA & EXILL - recent results 235 U data set GCDM Slope fit (Gaussian + Exponential) 112 keV  = 2.6(3) ns  = 2.2(2) ns 76 keV  = 2.7(3) ns  = 2.7(2) ns Error only fit error 112 keV PRD 9/2 -, 141 Xe Compton background

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 9 … where to continue? 90 Physics motivation - octupole “magic number” N=88 - new shell closure at N=90? 144 Xe Where? Cf fission at ANL (yields are not so promising) - LICORNE at Orsay

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 10 Region around N=88,90 S. Sarkar and M. Saha Sarkar, J. Phys.: Conf. Ser. 267, (2011) E(2 + ) in 136,138 Sn: G. S. Simpson, PRL (2014) Shell closure at N=90 W. Urban et al., Eur. Phys. J. A 16 (2003) 303 Octupole collectivity at N=88 - indicators are enhanced electric dipole moments - low energies in the odd isotopes results in longer lifetimes

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 11 E0 strengths E2 E0 E0 strength is shape-transition region around neutron-deficient Hg, Pb, Po If 2 + is below second 0 + measure lifetime of second could be in the ns range measure E2 intensity and branching ratio E2/E0 (requires electron spectrometer) Could be done at - ISOLDE (IDS + electron set-up) - JYFL (focal plane of separator) Example 30 Mg: lifetime: H. Mach, Eur. Phys. J. A 25, 105 (2005) E2/E0: W. Schwerdtfeger, PRL 103, (2009) 

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 12 Digital fast-timing CAEN fast digitiser - 32 channels - up to 5 GSamp/s more flexibility compared to analogue - CFD, leading edge (as in analogue) - SCC (purely digital, not yet tested for LaBr 3 ) - Least Mean Square Error (LMSE) -... easy to scale to larger arrays Guillermo Fernández Martínez Alexander Ignatov

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 13 Digital fast-timing Pulse processing for timing (... done offline)... in a nut shell: base line reconstruction low pass filter to interpolate between samples and reduce noise - convolution with Hamming window of length M - convolution repeated several times calculate difference between two signals within a ROI (one signal is moved in time by j time bins)

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 14 Digital fast-timing

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 15 Digital fast-timing

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 16 Digital fast-timing

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 17 Digital fast-timing

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 18 Digital fast-timing Best timing

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 19 Digital fast-timing First photo electron contains timing information  fraction of maximum derivative at the beginning of ROI is evaluated 2 LaBr 3 (1.5” x 1.5”), R9779 PMT, 22 Na source ( 2 x 511 keV) Best resolution  = 107 ps  = 76 ps / detector FWHM = 178 ps / detector

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 20 Digital fast-timing Digital leading edge discriminator - requires very low threshold for best results Best resolution  = 110 ps

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 21 LaBr 3 crystal from Kinheng Han-Bum Rhee / Alexander Ignatov

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 22 LaBr 3 crystal from Kinheng

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 23 LaBr 3 crystal from Kinheng R Na 1.5'x1.5' LaBr3(Ce) by Saint Gobain (SG) 1.5'x1.5' LaBr3(Ce) by Kinheng Crystal (KC) R9779 CAEN V1742 DIGITIZER anode

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 24 LaBr 3 crystal from Kinheng Leading edge discriminator

19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Kröll | TU Darmstadt | 25 … some kind of summary and outlook Rich data set from ILL... still many things to be analysed - Xe isotopes... higher states - other elements, e.g. Ba, Ce (and the odd Z too) at N=88,90... policy for analysis of isotopes not claimed by proposals Ideas for new experiments have to be worked out more carefully - neutron-rich nuclei north-west of 132 Sn - E0 strengths in neutron-deficient Hg, Pb, Po Work on digital algorithms has to be continued... also concerning the implementation on FPGAs for online operation Other materials / suppliers / readout - CeBr 3 - SiPM, APD