2 0 1 3 J I N S T 8 P 0 3 0 1 4

An array of eight Ge detectors for coincidence measurement s of γ rays from neutroncapture reactions has been constructed at the PF1B cold-neu tro facility of the Institut LaueLangevin. The detectors arranged in one plane every 45 ◦ can be used for angular correlation measurements. The neutron collimation line of the setup pro vides a neutron beam of 12 mm in diameter and the capture flux of about 10 8/(s×cm2) at the target position, with a negligible neutron halo. With the setup up to 10 9 γγ and up to 108 triple-γ coincidence events have been collected in a day measurement. Precise energy and efficiency calibratio ns up to 10 MeV are easily performed with 27Al(n,γ)28Al and35Cl(n,γ)36Cl reactions. Test measurements have shown that neutron bin ding energies can be determined with an accuracy down to a few e V and angular correlation coefficients measured with a precision down to a percent level. Th e triggerless data collected with a digital electronics and acquisition allows to determine ha lf-lives of excited levels in the nanoto microsecond range. The high resolving power of doubleand t riple-γ time coincidencesallows significant improvements of excitation schemes reported in previous(n,γ) works and complements high-resolutionγ-energy measurements at the double-crystal Bragg spectrom eter GAMS of ILL.

[1]  T. Materna,et al.  02+ band in 102Ru and the evolution of nuclear deformation in Ru isotopes , 2013 .

[2]  M. Günther,et al.  Refractive index of silicon at γ ray energies. , 2011, Physical review letters.

[3]  R. Frahm,et al.  Measurements of the pair production cross section close to the threshold energy , 2011 .

[4]  P. Mutti,et al.  A NEW FAST TRIGGERLESS ACQUISITION SYSTEM FOR LARGE DETECTOR ARRAYS , 2011 .

[5]  G. Pascovici,et al.  The mirror symmetric centroid difference method for picosecond lifetime measurements via γ―γ coincidences using very fast LaBr3(Ce) scintillator detectors , 2010 .

[6]  J. Krempel,et al.  A validity test of E = m ⋅ c2 , 2009 .

[7]  K. Schreckenbach,et al.  The Miracle of the Electron-Positron Pair Production Threshold , 2009 .

[8]  A. Smith,et al.  New isomers and medium-spin structure of the Y-95 nucleus , 2009 .

[9]  N. Schunck,et al.  Island of rare Earth nuclei with tetrahedral and octahedral symmetries: possible experimental evidence. , 2006, Physical review letters.

[10]  Technology,et al.  Precision measurement of the Si-29, S-33, and Cl-36 binding energies , 2005, nucl-ex/0507011.

[11]  A. H. Wapstra,et al.  The AME2003 atomic mass evaluation . (II). Tables, graphs and references , 2003 .

[12]  Z. Révay,et al.  Wide energy range efficiency calibration method for Ge detectors , 2002 .

[13]  N. Schunck,et al.  Nuclear tetrahedral symmetry: possibly present throughout the periodic table. , 2002, Physical review letters.

[14]  Z. Révay,et al.  66Ga: a standard for high-energy calibration of Ge detectors , 2002 .

[15]  E. Kessler,et al.  The GAMS4 flat crystal facility , 2001 .

[16]  F.,et al.  66 Ga: a Standard for High-Energy Calibration of Ge Detectors , 2001 .

[17]  D. Warner.  Nuclear Structure—The Future With Radioactive Beams , 2000, Journal of research of the National Institute of Standards and Technology.

[18]  H. Lehmann,et al.  The GRID Technique: Current Status and New Trends , 2000, Journal of research of the National Institute of Standards and Technology.

[19]  P. Endt.  SUPPLEMENT TO ENERGY LEVELS OF A = 21-44 NUCLEI. (VII) , 1998 .

[20]  J. Jolie,et al.  A MeV tunable gamma-ray source by Compton scattering , 1996 .

[21]  G. Barreau,et al.  Levels and gamma energies ofAl28studied by thermal neutron capture , 1982 .

[22]  B. Harmatz.  Nuclear data sheets for A=115 , 1980 .

[23]  D. Kocher.  Nuclear data sheets for A = 74 , 1976 .

[24]  S. Raman,et al.  Nuclear Data Sheets for A = 116 , 1975 .

[25]  W. Hamilton.  The Electromagnetic interaction in nuclear spectroscopy , 1975 .

[26]  K. Krane.  E 2M 1 Multipole Mixing Ratios of gamma Transitions in Even-Even Deformed Nuclei , 1973 .

[27]  R. M. Wheeler,et al.  Directional correlations of gamma radiations emitted from nuclear states oriented by nuclear reactions or cryogenic methods , 1973 .