E. Fiori

High count rate γ-ray spectroscopy with LaBr3:Ce scintillation detectors

Abstract The applicability of LaBr3:Ce detectors for high count rate γ - ray spectroscopy is investigated. Axa03xa0in.×3xa0in. LaBr3:Ce detector is used in a test setup with radioactive sources to study the dependence of energy resolution and photo peak efficiency on the overall count rate in the detector. Digitized traces were recorded using a 500xa0MHz FADC and analysed with digital signal processing methods. Good performance is obtained using standard techniques up to about 500xa0kHz counting rate. A pile-up correction method is applied to the data in order to further improve the capabilities at even higher rates with a focus on recovering the losses in efficiency due to signal pile-up. It is shown that γ - ray spectroscopy can be performed with only moderate lossen in efficiency and high resolution at count rates even above 1xa0MHz and that the performance can be enhanced in the region between 500xa0kHz and 10xa0MHz by using the applied pile-up correction techniques.

The high-efficiency γ-ray spectroscopy setup γ3 at HIγS

The existing Nuclear Resonance Fluorescence (NRF) setup at the HI{gamma}S facility at the Triangle Universities Nuclear Laboratory at Duke University has been extended in order to perform {gamma}-{gamma} coincidence experiments. The new setup combines large volume LaBr3:Ce detectors and high resolution HPGe detectors in a very close geometry to offer high efficiency, high energy resolution as well as high count rate capabilities at the same time. The combination of a highly efficient {gamma}-ray spectroscopy setup with the mono-energetic high-intensity photon beam of HI{gamma}S provides a worldwide unique experimental facility to investigate the {gamma}-decay pattern of dipole excitations in atomic nuclei. The performance of the new setup has been assessed by studying the nucleus sulfur at 8.125 MeV beam energy. The {gamma}-decay branching ratio from the

Particle identification using clustering algorithms

1^+

Transfer Reactions on Neutron‐rich Nuclei at REX‐ISOLDE

level at 8125.4 keV to the first excited

Investigation of the Photon Strength Function in 130 Te

2^+

Pulse shape analysis using CsI(Tl) crystals

state was determined to 15.7(3)%.

The high-efficiency {\gamma}-ray spectroscopy setup {\gamma}3 at HI{\gamma}S

Abstract A method that uses fuzzy clustering algorithms to achieve particle identification based on pulse shape analysis is presented. The fuzzy c-means clustering algorithm is used to compute mean (principal) pulse shapes induced by different particle species in an automatic and unsupervised fashion from a mixed set of data. A discrimination amplitude is proposed using these principal pulse shapes to identify the originating particle species of a detector pulse. Since this method does not make any assumptions about the specific features of the pulse shapes, it is very generic and suitable for multiple types of detectors. The method is applied to discriminate between photon- and proton-induced signals in CsI(Tl) scintillator detectors and the results are compared to the well-known integration method.

The high-efficiency spectroscopy setup y³ at Hiys

We report on one- and two-neutron transfer reactions to study the single-particle properties of nuclei at the border of the island of inversion. The (d,p)- and (t,p)-reactions in inverse kinematics on the neutron-rich isotope Mg-30, delivered as radioactive beam by the REX-ISOLDE facility, have been investigated. The outgoing protons have been detected and identified by a newly built array of Si detectors. The gamma-decay of excited states has been detected in coincidence by the MINIBALL array. First results for Mg-31 and from the search for the second, spherical, 0(+) state in Mg-32 are presented.

The high-efficiency spectroscopy setup at

The dipole strength distribution of 130Te was investigated with the method of Nuclear Resonance Fluorescence using continuous-energy bremsstrahlung at the Darmstadt High Intensity Photon Setup and quasi-monoenergetic photons at the High Intensity γ-Ray Source. The average decay properties were determined between 5.50 and 8.15 MeV and compared to simulations within the statistical model.

The high-efficiency γ-rayγ-ray spectroscopy setup γ3γ3 at HIγSHIγS

The decay time of CsI(Tl) scintillating material consists of more than a single exponential component. The ratio between the intensity of these components varies as a function of the ionizing power of the absorbed particles, such as γ-rays or protons, and the temperature. This property can therefore be used for particle discrimination and for temperature monitoring, using pulse shape analysis. An unsupervised method that uses fuzzy clustering algorithms for particle identification based on pulse shape analysis is presented. The method is applied to discriminate between photon- and proton-induced signals in CsI(Tl) scintillator detectors. The first results of a method that uses pulse shape analysis for correcting the temperature-dependent gain effect of the detector are also presented. The method aims at conserving a good energy resolution in a temperature varying environment without the need to measure the temperature of the detector externally.