1,721,208 research outputs found
In-beam test and imaging capabilities of the AGATA prototype detector
Full text linkHigh-resolution gamma-ray spectroscopy is one of the most powerful and sensitive tools to investigate Nuclear Structure. Significant progress in this field was achieved through the use of arrays of Compton-suppressed high purity germanium detectors, leading for instance to the discovery of phenomena such as nuclear superdeformation. However, it is apparent that the present generation devices are not suited to the expected experimental conditions at the planned and under construction radioactive ion beam facilities. Devices with higher efficiency and sensitivity should be developed. The solution which has been proposed since the mid-nineties relies on the possibility to determine the position and the energy deposition of the individual interaction points of a photon within a germanium crystal, and on the capability to reconstruct the photon scattering sequence through powerful signal analysis algorithms. The results of Monte Carlo simulations suggest that indeed an array of germanium detectors using such techniques, which are known as Pulse Shape Analysis and gamma-ray tracking, will reach the performance required to operate effectively at the future radioactive ion beam facilities. Presently, two major projects aim at the construction of an array of germanium detectors based on the pulse shape analysis and gamma ’–ray tracking techniques, namely GRETA in the USA and AGATA in Europe.
The present work describes the results obtained during the first in-beam test performed with the prototype detector of AGATA. The goal of the experiment was essentially to measure the precision on the position of the individual interaction points extracted with pulse shape analysis algorithms.
Such a precision plays an essential role in determining the overall performance of the array.
Chapter 1 deals briefly with the most actual topics in Nuclear Structure studies, pointing to the necessity to develop new generation radioactive ion beam facilities, as well as new detection systems such as AGATA.
The status of the AGATA project is reviewed in Chapter 2, together with a short introduction to the principles of gamma-ray tracking and of pulse shape analysis.
The results from the in-beam test with the AGATA prototype detector are presented in Chapter 3, where the data analysis procedure is described in detail.
Finally, in Chapter 4 a possible technique to extract the position resolution of the AGATA detectors through Compton imaging techniques is presented, together with some preliminary results
Recent results from the Monte Carlo simulations for the AGATA array
No full textA Monte Carlo code based on the C++ classes of Geant4 has been developed to meet the requirements of the AGATA project, which has the goal to develop an array of highly segmented high-purity germanium detectors based on the novel concepts of pulse shape analysis and γ-ray tracking. The code has been used to optimize the final geometry of the array and to evaluate realistically its performance under a wide range of experimental conditions. Some results of the extensive simulation work are presented here. © 2006 American Institute of Physics
Pulse shape analysis for segmented germanium detectors implemented in graphics processing units
No full textPosition sensitive highly segmented germanium detectors constitute the state-of-the-art of the technology employed for γ-spectroscopy studies. The operation of large spectrometers composed of tens to hundreds of such detectors demands enormous amounts of computing power for the digital treatment of the signals. The use of Graphics Processing Units (GPUs) has been evaluated as a cost-effective solution to meet such requirements. Different implementations and the hardware constraints limiting the performance of the system are examined. © 2013 Elsevier B.V
Shape coexistence far from stability
No full textRecent results on the gamma-ray spectroscopy of the neutron-rich nucleus 67Co, populated through multi-nucleon transfer reactions by bombarding a 238U target with a 460 MeV 70Zn beam at the Legnaro National Laboratory, are presented. The development of deformation in Co isotopes approaching the N=40 subshell closure is discussed within the shell model framework in a very large model space. These calculations are able to describe with good accuracy the excited states observed in 67Co, at the edge of the island of inversion at N=40, where a low lying highly deformed band coexists with a spherical structure. © 2012 American Institute of Physics
Experimental test of the background rejection, through imaging capability, of a highly segmented AGATA germanium detector
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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