1,017 research outputs found
AGATA, Technical Proposal for an Advanced Gamma Tracking Array for the European Gamma Spectroscopy Community
International audienceAn Advanced GAmma-ray Tracking Array, AGATA, is proposed for high-resolution γ-ray spectroscopy with exotic beams. AGATA will employ highly segmented Ge detectors as well as fully digital electronics and relies on newly developed pulse-shape analysis and tracking methods. The array is being designed in a way that it provides optimal properties for nuclear structure experiments in a wide range of beam velocities (from stopped to v/c ≈ 50%), almost independent of beam quality and background conditions. Selectivity and sensitivity of AGATA will be superior to any existing γ-array by several orders of magnitude. Hence, it will be for a long time a rich source for nuclear structure physics providing the means for new discoveries and opening challenging new perspectives. This document is the initial proposal sent to the European Commission to obtain the necessary funds for the project
Lifetime measurements in Co and Co
Lifetimes of the and states in Co and the
state in Co were measured using the recoil distance Doppler
shift and the differential decay curve methods. The nuclei were populated by
multi-nucleon transfer reactions in inverse kinematics. Gamma rays were
measured with the EXOGAM Ge array and the recoiling fragments were fully
identified using the large-acceptance VAMOS spectrometer. The E2 transition
probabilities from the and states to the ground
state could be extracted in Co as well as an upper limit for the
(E2) value in Co. The experimental
results were compared to large-scale shell-model calculations in the and
model spaces, allowing to draw conclusions on the single-particle
or collective nature of the various states.Comment: 8 pages, 8 figures, 1 table, accepted for publication in Physical
Review
High-spin structure of Xe 134
A. Vogt et al. ; 12 págs.; 9 figs.; 1 tab.Detailed spectroscopic information on the N∼82 nuclei is necessary to benchmark shell-model calculations in the region. The nuclear structure above long-lived isomers in Xe134 is investigated after multinucleon transfer (MNT) and actinide fission. Xenon-134 was populated as (i) a transfer product in Xe136+U238 and Xe136+Pb208 MNT reactions and (ii) as a fission product in the Xe136+U238 reaction employing the high-resolution Advanced Gamma Tracking Array (AGATA). Trajectory reconstruction has been applied for the complete identification of beamlike transfer products with the magnetic spectrometer PRISMA. The Xe136+Pt198 MNT reaction was studied with the γ-ray spectrometer GAMMASPHERE in combination with the gas detector array Compact Heavy Ion Counter (CHICO). Several high-spin states in Xe134 on top of the two long-lived isomers are discovered based on γγ-coincidence relationships and information on the γ-ray angular distributions as well as excitation energies from the total kinetic energy loss and fission fragments. The revised level scheme of Xe134 is extended up to an excitation energy of 5.832 MeV with tentative spin-parity assignments up to 16+. Previous assignments of states above the 7- isomer are revised. Latest shell-model calculations employing two different effective interactions reproduce the experimental findings and support the new spin and parity assignments.The research leading to these results has received funding
from the German BMBF under Contract No. 05P12PKFNE
TP4, from the European Union Seventh Framework Programme
FP7/2007–2013 under Grant Agreement No. 262010 -
ENSAR, from the Spanish Ministerio de Ciencia e Innovación
under Contract No. FPA2011-29854-C04, from the Spanish
Ministerio de EconomÃa y Competitividad under Contract No.
FPA2014-57196-C5, from the Bonn-Cologne Graduate School
of Physics and Astronomy (BCGS), from the UK Science
and Technology Facilities Council (STFC), and from the US
National Science Foundation (NSF). One of the authors (A.
Gadea) has been supported by the Generalitat Valenciana,
Spain, under Grant No. PROMETEOII/2014/019 and EU
under the FEDER program.Peer Reviewe
Characterizing Universal Reconfigurability of Modular Pivoting Robots
We give both efficient algorithms and hardness results for reconfiguring
between two connected configurations of modules in the hexagonal grid. The
reconfiguration moves that we consider are "pivots", where a hexagonal module
rotates around a vertex shared with another module. Following prior work on
modular robots, we define two natural sets of hexagon pivoting moves of
increasing power: restricted and monkey moves. When we allow both moves, we
present the first universal reconfiguration algorithm, which transforms between
any two connected configurations using monkey moves. This result
strongly contrasts the analogous problem for squares, where there are rigid
examples that do not have a single pivoting move preserving connectivity. On
the other hand, if we only allow restricted moves, we prove that the
reconfiguration problem becomes PSPACE-complete. Moreover, we show that, in
contrast to hexagons, the reconfiguration problem for pivoting squares is
PSPACE-complete regardless of the set of pivoting moves allowed. In the
process, we strengthen the reduction framework of Demaine et al. [FUN'18] that
we consider of independent interest
Accountability, Strategy, and International Non-Governmental Organizations
Increased prominence and greater influence expose international non-governmental development and environmental organizations (INGOs) to increased demands for accountability from a wide variety of stakeholdersdonors, beneficiaries, staffs, and partners among others. This paper focuses on developing the concept of INGO accountability, first as an abstract concept and then as a strategic idea with very different implications for different INGO strategies. We examine those implications for INGOs that emphasize service delivery, capacity-building, and policy influence. We propose that INGOs committed to service delivery may owe more accountability to donors and service regulators; capacity-building INGOs may be particularly obligated to clients whose capacities are being enhanced; and policy influence INGOs may be especially accountable to political constituencies and to influence targets. INGOs that are expanding their activities to include new initiatives may need to reorganize their accountability systems to implement their strategies effectively. This publication is Hauser Center Working Paper No. 7. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers
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