558 research outputs found
Detection
This review on second- and third-generation multidetectors devoted to heavy-ion collisions aims to cover the last twenty years. The presented list of devices is not exhaustive but regroups most of the techniques used during this period for nuclear reactions at intermediate energy (â 10A MeV to 1A GeV), both for charged-particle and neutron detection. The main part will be devoted to 4Ï multidetectors, projectile decay fragmentation, high-resolution magnetic spectrometers, auxiliary detectors and neutron detection. The last part will present the progress in electronics and detection in view of the construction of future-generation detectors
Exclusive Studies of Charged-Particle Emission in 1-H and 3-He-Induced Reactions on Heavy Nuclei
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Emissioin of Intermediate Mass Fragments During Fission
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
IMF Emission in the 14-N + nat-Ag, Au Reactions at E/A = 60-100 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Fragment Isospin as a Probe of Heavy-Ion Collisions
Isotope ratios of fragments produced at mid-rapidity in peripheral and
central collisions of 114Cd ions with 92Mo and 98Mo target nuclei at E/A = 50
MeV are compared. Neutron-rich isotopes are preferentially produced in central
collisions as compared to peripheral collisions. The influence of the size (A),
density, N/Z, E*/A, and Eflow/A of the emitting source on the measured isotope
ratios was explored by comparison with a statistical model (SMM). The
mid-rapidity region associated with peripheral collisions does not appear to be
neutron-enriched relative to central collisions.Comment: 12 pages including figure
Root dentinal microcracks: a post-extraction experimental phenomenon?
Aim
To investigate the prevalence, location and pattern of preâexisting microcracks in nonâendodontically treated teeth from fresh cadavers. Microâcomputed tomography (microâCT) technology was used as the analytical tool enabling full screening of the root dentine with the teeth retained in their original alveolar socket.
Methodology
As a pilot study and to validate the present method, a series of 4 highâresolution scans were performed on one boneâblock specimen with teeth collected postâmortem: (i) entire boneâblock including the teeth, (ii) second molar tooth extracted atraumatically from the boneâblock, (iii) extracted tooth dehydrated to induce dentinal defects and (iv) entire boneâblock following reinsertion of the extracted tooth into its matching alveolar socket. In the main study, fortyâtwo dentoalveolar maxillary and mandibular boneâblocks each containing 3â5 adjacent teeth (a total of 178 teeth) were collected postâmortem and scanned in a microâCT device. All crossâsection images of the 178 teeth (n = 65 530) were screened from the cementoenamel junction to the apex to identify the presence of dentinal defects.
Results
In the pilot study, the microcracks observable when the dehydrated tooth was outside the boneâblock remained detectable when the entire boneâblock plus reinserted tooth was scanned. This means that the screening process revealed the presence of the same microcracks in both experimental situations (the tooth outside and inside the maxillary boneâblock). From a total of 178 teeth in the boneâblocks removed from cadavers, 65 530 crossâsectional images were analysed and no dentinal microcracks were detected.
Conclusions
This in situ cadaveric model revealed the lack of preâexisting dentinal microcracks in nonâendodontically treated teeth. Thus, the finding of dentinal microcracks observed in previous crossâsectional images of stored extracted teeth is unsound and not valid. It should be assumed that microcracks observed in stored extracted teeth subjected to root canal procedures are a result of the extraction process and/or the postâextraction storage conditions. Therefore, as a consequence, the presence of such dentinal microcracks in stored extracted teeth â observable in crossâsectional images of the roots â should be referred to as experimental dentinal microcracks
Fragment Production in Non-central Collisions of Intermediate Energy Heavy Ions
The defining characteristics of fragment emission resulting from the
non-central collision of 114Cd ions with 92Mo target nuclei at E/A = 50 MeV are
presented. Charge correlations and average relative velocities for mid-velocity
fragment emission exhibit significant differences when compared to standard
statistical decay. These differences associated with similar velocity
dissipation are indicative of the influence of the entrance channel dynamics on
the fragment production process
Excitation and decay of projectile-like fragments formed in dissipative peripheral collisions at intermediate energies
Projectile-like fragments (PLF:15<=Z<=46) formed in peripheral and
mid-peripheral collisions of 114Cd projectiles with 92Mo nuclei at E/A=50 MeV
have been detected at very forward angles, 2.1 deg.<=theta_lab<=4.2 deg.
Calorimetric analysis of the charged particles observed in coincidence with the
PLF reveals that the excitation of the primary PLF is strongly related to its
velocity damping. Furthermore, for a given V_PLF*, its excitation is not
related to its size, Z_PLF*. For the largest velocity damping, the excitation
energy attained is large, approximately commensurate with a system at the
limiting temperatureComment: 5 pages, 6 figure
Local singlets, frustration, and unconventional superconductivity in the organic charge-transfer solids
We suggest that superconductivity (SC) in the organic charge transfer solids
(CTS) is reached from a Bond-Charge Density Wave (BCDW). We discuss an
effective model for the BCDW to SC transition, an attractive U extended Hubbard
Hamiltonian with repulsive nearest neighbor interaction V. We discuss
experimental consequences of the theory for different classes of CTS
superconductors as well as related inorganic materials.Comment: 4 pages, 2 figures, ECRYS 200
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