Nuclear Experiment

New submissions

Submissions received from Fri 28 Nov 08 to Mon 1 Dec 08, announced Tue, 2 Dec 08
[ total of 9 entries: 1-9 ]
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New submissions for Tue, 2 Dec 08

[1]  arXiv:0812.0031 [ps, pdf, other]
Title: Spin Structure Moments of the Proton and Deuteron
Authors: K. Slifer, O.A. Rondon, A. Aghalaryan, A. Ahmidouch, R. Asaturyan, F. Bloch, W. Boeglin, P. Bosted, C. Carasco, R. Carlini, J. Cha, J.P. Chen, M.E. Christy, L. Cole, L. Coman, D. Crabb, S. Danagoulian, D. Day, J. Dunne, M. Elaasar, R. Ent, H. Fenker, E. Frlez, D. Gaskell, L. Gan, J. Gomez, B. Hu, J. Jourdan, M. K. Jones, C. Keith, C.E. Keppel, M. Khandaker, A. Klein, L. Kramer, Y. Liang, J. Lichtenstadt, R. Lindgren, D. Mack, P. McKee, D. McNulty, D. Meekins, H. Mkrtchyan, R. Nasseripour, I. Niculescu, K. Normand, B. Norum, D. Pocanic, Y. Prok, B. Raue, J. Reinhold, J. Roche, D. Kiselev (nee Rohe), N. Savvinov, B. Sawatzky, M. Seely, I. Sick, C. Smith, G. Smith, S. Stepanyan, L. Tang, S. Tajima, G. Testa, W. Vulcan, K. Wang, G. Warren, F.R. Wesselmann, S. Wood, C. Yan, L. Yuan, J. Yun, M. Zeier, et al. (1 additional author not shown)
Comments: v3.0
Subjects: Nuclear Experiment (nucl-ex)

Moments of the spin structure functions g1 and g2 of the proton and deuteron have been measured in the resonance region at intermediate four momentum transfer. We perform a Nachtmann moment analysis of this data, along with isovector and isoscalar combinations, in order to rigorously account for target mass effects. This analysis provides the first definitive evidence for dynamic higher twists.

[2]  arXiv:0812.0054 [ps, pdf, other]
Title: Multi-pronged events from Coulomb fission of nuclei at very low energies
Authors: B. Basu, S. Dey, D. Gupta, A. Maulik, S. Raha, Swapan K. Saha, D. Syam
Comments: 4 pages, 1 figure
Subjects: Nuclear Experiment (nucl-ex)

Multi-pronged tracks have been recorded in the polyethylene terephthalate (C$_{10}$H$_8$O$_4$)$_n$ solid state nuclear track detector by exposure to a $^{252}$Cf fission source. After chemical etching, two-prong to six-pronged tracks along with single tracks have been observed under the optical microscope. We carried out a systematic study to understand the origin of the prongs. The track detectors were coated with metals (Cu, Ag and Pb) and were exposed to $^{252}$Cf source. After chemical etching two-prong to four pronged tracks were observed in each plate. We believe that at this very low energy of the order of 1 MeV/A, Coulomb fission is the only plausible explanation for the origin of such multi-pronged tracks.

[3]  arXiv:0812.0091 [pdf, other]
Title: AGATA: Gamma-ray tracking in segmented HPGe detectors
Authors: P.-A. Söderström, A. Al-Adili, J. Nyberg, F. Recchia, E. Farnea, A. Gadea
Comments: 10 pages, 6 figures. To appear in the proceedings of 17th International Workshop on Vertex detectors July 28 - 1 August 2008 Uto Island, Sweden
Subjects: Nuclear Experiment (nucl-ex)

The next generation of radioactive ion beam facilities, which will give experimental access to many exotic nuclei, are presently being developed. At the same time the next generation of high resolution gamma-ray spectrometers, based on gamma-ray tracking, for studying the structure of these exotic nuclei are being developed. One of the main differences in tracking of $\gamma$ rays versus charged particles is that the gamma rays do not deposit their energy "continuously" in the detector, but in a few discrete steps. Also, in the field of nuclear spectroscopy, the location of the source is mostly well known while the exact interaction position in the detector is the unknown quantity. This makes the challenges of gamma-ray tracking in germanium somewhat different compared to vertexing in silicon detectors. In these proceedings we present the methods for determining the 3D interaction positions in the detector and how these are used to reconstruct the gamma-ray tracks in the AGATA detector array. We also present preliminary simulation results of a proposed in-beam method to measure the interaction position resolution in the germanium detectors.

[4]  arXiv:0812.0236 [ps, pdf, other]
Title: Fragmentation cross sections of Fe^{26+}, Si^{14+} and C^{6+} ions of 0.3-10 A GeV on CR39, polyethylene and aluminum targets
Authors: Miriam Giorgini
Comments: 4 pages, 5 eps figures. Talk given at the 24th International Conference on Nuclear Tracks in Solids, Bologna, Italy, 1-5 September 2008
Subjects: Nuclear Experiment (nucl-ex)

New measurements of the total and partial fragmentation cross sections in the energy range 0.3-10 A GeV of Fe^{26+}, Si^{14+} and C^{6+} beams on polyethylene, CR39 and aluminum targets are presented. The exposures were made at Brookhaven National Laboratory (BNL), USA, and Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. The CR39 nuclear track detectors were used to identify the incident and survived beams and their fragments. The total fragmentation cross sections for all targets are almost energy independent while they depend on the target mass. The measured partial fragmentation cross sections are also discussed.

[5]  arXiv:0812.0347 [pdf]
Title: The point spread function of electrons in a magnetic field, and the beta-decay of free neutrons
Authors: D. Dubbers, B. Maerkisch, F. Friedl, H. Abele
Comments: 10 pages, 8 figures
Subjects: Nuclear Experiment (nucl-ex)

When a uniform magnetic field is used to guide electrons from a beta-emitter to a detector, the electrons on the detector are distributed over an area whose size is larger than the size of the source by up to four radii of gyration, and more if also backscattered electrons are registered. This blurring of the image of the electron source can be described by a suitable point spread function (PSF). This rather general problem is investigated in the context of newly developed neutron beta-decay spectrometers. We derive this 'magnetic' PSF for an active neutron decay volume coupled to an electron detector by a magnetic field. We then investigate the effect of limited detector size on measured neutron decay correlation parameters like the beta-decay asymmetry. To our surprise we find that in a typical spectrometer setup, even when detector size is as small as the size of the source, then this will change the asymmetry by less than 10-3.

Cross-lists for Tue, 2 Dec 08

[6]  arXiv:0811.1240 (cross-list from nucl-th) [ps, pdf, other]
Title: Eigenvalues correlations and the distribution of ground state angular momenta for random many-body quantum systems
Authors: J. Barea, R. Bijker, A. Frank
Comments: 4 pages, 1 figure, 1 table, submitted
Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)

The observed preponderance of ground states with angular momentum L=0 in many-body quantum systems with random two-body interactions is analyzed in terms of correlation coefficients (covariances) among different eigenstates. The recent geometric analysis of Chau et al. is reinterpreted in purely statistical terms, allowing to relate this result with other unexpected statistical effects in correlated data. It is shown that the present method which, strictly speaking, is valid for diagonal interactions only, can be extended to non-diagonal interactions by means of perturbation theory.

[7]  arXiv:0811.4671 (cross-list from nucl-th) [ps, pdf, other]
Title: New supersymmetric quartet of nuclei in the A=190 mass region
Authors: J. Barea, R. Bijker, A. Frank, G. Graw, R. Hertenberger, H. F. Wirth, S. Christen, J. Jolie, D. Tonev, M. Balodis, J. Berzins, N. Kramere, T. Von Egidy
Comments: 5 pages, 5 figures, submitted
Subjects: Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)

We present evidence for a new supersymmetric quartet in the A=190 region of the nuclear mass table. New experimental information on transfer and neutron capture reactions to the odd-odd nucleaus 194 Ir strongly suggests the existence of a new supersymmetric quartet, consisting of the 192,193 Os and 193,194 Ir nuclei. We make explicit predictions for the odd-neutron nucleus 193 Os, and suggest that its spectroscopic properties be measured in dedicated experiments.

Replacements for Tue, 2 Dec 08

[8]  arXiv:0807.0034 (replaced) [pdf]
Title: IceCube: A Cubic Kilometer Radiation Detector
Authors: Spencer R. Klein, for the IceCube Collaboration
Comments: Revised version, with details added, per referee request. 8 pages, presented at SORMA West 2008 (Symposium on Radiation Measurement and Applications)
Subjects: Instrumentation and Detectors (physics.ins-det); Astrophysics (astro-ph); Nuclear Experiment (nucl-ex)
[9]  arXiv:0811.1283 (replaced) [ps, pdf, other]
Title: Search for Fingerprints of Tetrahedral Symmetry in $^{156}Gd$
Authors: Q.T. Doan (IPNL), D. Curien (DRS-IPHC), O. Stezowski (IPNL), J. Dudek (DRS-IPHC), K. Mazurek (Niewodniczanski Institute of Nuclear Physics), A. Gozdz (Maria Curie-Sklodowska Univ.), J. Piot (DRS-IPHC), G. Duchene (DRS-IPHC), B. Gall (DRS-IPHC), H. Molique (DRS-IPHC), M. Richet (DRS-IPHC), P. Medina (DRS-IPHC), D. Guinet (IPNL), N. Redon (IPNL), C. Schmitt (IPNL), P. Jones (University of Jyvaskyl), R. Julin (University of Jyvaskyl), P. Peura (University of Jyvaskyl), S. Ketelhut (University of Jyvaskyl), M. Nyman (University of Jyvaskyl), U. Jakobsson (University of Jyvaskyl), A. Maj (Niewodniczanski Institute of Nuclear Physics), K. Zuber (Niewodniczanski Institute of Nuclear Physics), P. Bednarczyk (Niewodniczanski Institute of Nuclear Physics), N. Schunck (Physics Division, ORNL), J. Dobaczewski (University of Jyvaskyl, Warsaw Univ.), et al. (5 additional authors not shown)
Comments: presented by Q.T. Doan at XLII Zakopane School of Physics: Breaking Frontiers: Submicron Structures in Physics and Biology, May 2008. 5 pages, minor corrections. To be published in the proceedings
Subjects: Nuclear Experiment (nucl-ex)
[ total of 9 entries: 1-9 ]
[ showing up to 2000 entries per page: fewer | more ]