Ideas for fast-timing experiments from TU Darmstadt and recent
results and technical developments Thorsten Krll (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 Slide 2 19-20 March 2015 | FATIMA meeting, NPL Teddington
(UK) | Thorsten Krll | 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) Slide 3 19-20 March
2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Krll | TU
Darmstadt | 3 FATIMA & EXILL - recent results Slide 4 19-20
March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Krll |
TU Darmstadt | 4 FATIMA & EXILL - recent results Slide 5 19-20
March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Krll |
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. Rgis NIM A 726, 191
(2013) Slide 6 19-20 March 2015 | FATIMA meeting, NPL Teddington
(UK) | Thorsten Krll | TU Darmstadt | 6 FATIMA & EXILL - recent
results 76 keV 112 keV Slide 7 19-20 March 2015 | FATIMA meeting,
NPL Teddington (UK) | Thorsten Krll | TU Darmstadt | 7 FATIMA &
EXILL - recent results Slide 8 19-20 March 2015 | FATIMA meeting,
NPL Teddington (UK) | Thorsten Krll | 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 Slide 9 19-20 March 2015 | FATIMA meeting, NPL
Teddington (UK) | Thorsten Krll | TU Darmstadt | 9 where to
continue? 90 Physics motivation - octupole magic number N=88 - new
shell closure at N=90? 144 Xe Where? - 252 Cf fission at ANL
(yields are not so promising) - LICORNE at Orsay Slide 10 19-20
March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Krll |
TU Darmstadt | 10 Region around N=88,90 S. Sarkar and M. Saha
Sarkar, J. Phys.: Conf. Ser. 267, 012040 (2011) E(2 + ) in 136,138
Sn: G. S. Simpson, PRL 132502 (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 Slide 11 19-20 March
2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Krll | TU
Darmstadt | 11 E0 strengths 0+0+ 2+2+ 0+0+ E2 E0 E0 strength is
shape-transition region around neutron-deficient Hg, Pb, Po If 2 +
is below second 0 + measure lifetime of second 0 +... 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, 012501 (2009) Slide 12 19-20 March 2015 |
FATIMA meeting, NPL Teddington (UK) | Thorsten Krll | 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 Fernndez Martnez Alexander Ignatov Slide 13 19-20
March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Krll |
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) Slide 14 19-20 March
2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten Krll | TU
Darmstadt | 14 Digital fast-timing Slide 15 19-20 March 2015 |
FATIMA meeting, NPL Teddington (UK) | Thorsten Krll | TU Darmstadt
| 15 Digital fast-timing Slide 16 19-20 March 2015 | FATIMA
meeting, NPL Teddington (UK) | Thorsten Krll | TU Darmstadt | 16
Digital fast-timing Slide 17 19-20 March 2015 | FATIMA meeting, NPL
Teddington (UK) | Thorsten Krll | TU Darmstadt | 17 Digital
fast-timing Slide 18 19-20 March 2015 | FATIMA meeting, NPL
Teddington (UK) | Thorsten Krll | TU Darmstadt | 18 Digital
fast-timing Best timing Slide 19 19-20 March 2015 | FATIMA meeting,
NPL Teddington (UK) | Thorsten Krll | 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
Slide 20 19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) |
Thorsten Krll | TU Darmstadt | 20 Digital fast-timing Digital
leading edge discriminator - requires very low threshold for best
results Best resolution = 110 ps Slide 21 19-20 March 2015 | FATIMA
meeting, NPL Teddington (UK) | Thorsten Krll | TU Darmstadt | 21
LaBr 3 crystal from Kinheng Han-Bum Rhee / Alexander Ignatov Slide
22 19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) |
Thorsten Krll | TU Darmstadt | 22 LaBr 3 crystal from Kinheng Slide
23 19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) |
Thorsten Krll | TU Darmstadt | 23 LaBr 3 crystal from Kinheng R9779
22 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 Slide 24
19-20 March 2015 | FATIMA meeting, NPL Teddington (UK) | Thorsten
Krll | TU Darmstadt | 24 LaBr 3 crystal from Kinheng Leading edge
discriminator Slide 25 19-20 March 2015 | FATIMA meeting, NPL
Teddington (UK) | Thorsten Krll | 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
