| 1. |
- Aggarwal, M. M., et al.
(författare)
-
Event-by-event charged-neutral fluctuations in Pb plus Pb collisions at 158 A GeV
- 2011
-
Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 701:3, s. 300-305
-
Tidskriftsartikel (refereegranskat)abstract
- Charged particles and photons have been measured in central Pb + Pb collisions at 158 A GeV in a common (eta-phi)-phase space region in the WA98 experiment at the CERN SPS. The measured distributions have been analyzed to quantify the frequency with which phase space regions of varying sizes have either small or large neutral pion fraction. The measured results are compared with VENUS model simulated events and with mixed events. Events with both large and small charged-neutral fluctuations are observed to occur more frequently than expected statistically, as deduced from mixed events, or as predicted by model simulations, with the difference becoming more prominent with decreasing size of the A Delta eta-Delta phi region. (C) 2011 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Aggarwal, M. M., et al.
(författare)
-
Photon and eta production in p plus Pb and p plus C collisions at root(NN)-N-S=17.4 GeV
- 2013
-
Ingår i: Nuclear Physics, Section A. - : Elsevier BV. - 0375-9474. ; 898, s. 14-23
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of direct photon production in p + Pb and p + C collisions at root(NN)-N-s = 17.4 GeV are presented. Upper limits on the direct photon yield as a function of p(T) are derived and compared to the results for Pb + Pb collisions at root(NN)-N-s = 17.3 GeV. The production of the eta meson, which is an important input to the direct photon signal extraction, has been determined in the eta -> 2 gamma channel for p + C collisions at root(NN)-N-s = 17.4 GeV. (c) 2012 Elsevier B.V. All rights reserved.
|
|
| 3. |
- Hinke, C. B., et al.
(författare)
-
Superallowed Gamow-Teller decay of the doubly magic nucleus 100Sn
- 2012
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 486:7403, s. 341-345
-
Tidskriftsartikel (refereegranskat)abstract
- The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During beta(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of Sn-100, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the beta-decay of Sn-100, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear beta-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, In-100, are well reproduced by modern, large-scale shell model calculations.
|
|
| 4. |
|
|
| 5. |
- Schulte, Peter, et al.
(författare)
-
Cretaceous Extinctions: Evidence Overlooked Response
- 2010
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 328:5981, s. 975-976
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
- Schulte, Peter, et al.
(författare)
-
The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary
- 2010
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 327:5970, s. 1214-1218
-
Tidskriftsartikel (refereegranskat)abstract
- The Cretaceous-Paleogene boundary similar to 65.5 million years ago marks one of the three largest mass extinctions in the past 500 million years. The extinction event coincided with a large asteroid impact at Chicxulub, Mexico, and occurred within the time of Deccan flood basalt volcanism in India. Here, we synthesize records of the global stratigraphy across this boundary to assess the proposed causes of the mass extinction. Notably, a single ejecta-rich deposit compositionally linked to the Chicxulub impact is globally distributed at the Cretaceous-Paleogene boundary. The temporal match between the ejecta layer and the onset of the extinctions and the agreement of ecological patterns in the fossil record with modeled environmental perturbations (for example, darkness and cooling) lead us to conclude that the Chicxulub impact triggered the mass extinction.
|
|
| 7. |
- Nishimura, Y., et al.
(författare)
-
Estimation of magnetic field mapping accuracy using the pulsating aurora-chorus connection
- 2011
-
Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 38, s. L14110-
-
Tidskriftsartikel (refereegranskat)abstract
- Although magnetic field models are widely used in magnetosphere-ionosphere coupling studies to perform field-line mapping, their accuracy has been difficult to estimate experimentally. Taking advantage of the high correlation between lower-band chorus and pulsating aurora, we located the THEMIS spacecraft footprint within similar to km accuracy and calculated the differences from mappings given in widely-used Tsyganenko models. Using 13 conjunctions of the THEMIS spacecraft and ground-based imagers, we found that the Tsyganenko model footprints were located within 1 degrees-2 degrees magnetic latitude and 0.1-0.2 h magnetic local time of our derived footprint. The deviation between the footprints has a consistent dependence on geomagnetic activity. Our results showed that the real magnetic field tends to be less stretched than that in the Tsyganenko models during quiet times and comparable to or more stretched during disturbed times. This approach can be used to advance modeling of field lines that connect to the near-Earth plasma sheet.
|
|
| 8. |
- Nishimura, Y., et al.
(författare)
-
Identifying the Driver of Pulsating Aurora
- 2010
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 330:6000, s. 81-84
-
Tidskriftsartikel (refereegranskat)abstract
- Pulsating aurora, a spectacular emission that appears as blinking of the upper atmosphere in the polar regions, is known to be excited by modulated, downward-streaming electrons. Despite its distinctive feature, identifying the driver of the electron precipitation has been a long-standing problem. Using coordinated satellite and ground-based all-sky imager observations from the THEMIS mission, we provide direct evidence that a naturally occurring electromagnetic wave, lower-band chorus, can drive pulsating aurora. Because the waves at a given equatorial location in space correlate with a single pulsating auroral patch in the upper atmosphere, our findings can also be used to constrain magnetic field models with much higher accuracy than has previously been possible.
|
|
| 9. |
- Nishimura, Y., et al.
(författare)
-
Multievent study of the correlation between pulsating aurora and whistler mode chorus emissions
- 2011
-
Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116, s. A11221-
-
Tidskriftsartikel (refereegranskat)abstract
- A multievent study was performed using conjugate measurements of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft and an all-sky imager during periods of intense lower-band chorus waves. The thirteen identified cases support our previous finding, based on two events, that the intensity modulation of lower-band chorus near the magnetic equator is highly correlated with quasiperiodic pulsating auroral emissions near the spacecraft's magnetic footprint, indicating that lower-band chorus is the driver of the pulsating aurora. Furthermore, we identified a fortuitous measurement made simultaneously by two THEMIS spacecraft with small spatial separation. The two spacecraft were found to be located in a single pulsating chorus patch and the spacecraft footprints were in the same pulsating auroral patch when intense chorus bursts were measured simultaneously, whereas only one of the spacecraft's footprints was in a patch when the other spacecraft did not detect intense chorus. On the basis of this event, we can estimate the pulsating chorus patch size by mapping the pulsating auroral patches from the ionosphere toward the magnetic equator, giving a roughly circular region of similar to 5000 km diameter for corresponding azimuthally elongated patches with similar to 100 km size in the ionosphere. Using a ray-tracing-based calculation of the divergence of chorus raypaths from a point source, together with the corresponding resonant energies, we found that the chorus patch size is most probably not a result of ray divergence but a property of the wave excitation region.
|
|
| 10. |
- Fukuda, M., et al.
(författare)
-
Reaction cross section studies at NIRS and RIBF
- 2010
-
Ingår i: American Institute of Physics Conference Series. - American Institute of Physics : AIP. ; , s. 270-273
-
Konferensbidrag (refereegranskat)abstract
- Reaction cross sections for stable nuclei at intermediate energies have been measured precisely and systematically. The data have been found to be reproduced nicely by the optical‐limit approximation of Glauber theory modified to include the nucleon multiple scattering effect and the Fermi‐motion effect. Applying this prescription, the nucleon density distribution of 17Ne has been studied. The surface structure of 8B and 11Be has been also studied using this prescription and hydrogen targets. Using the RIBF that has just started application to studies of exotic nuclei, neutron‐rich Ne isotopes around the Island of Inversion have been investigated through measurements of their interaction cross sections.
|
|
