Other
Scientific paper
Jan 1990
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1990phdt........54n&link_type=abstract
Thesis (PH.D.)--MICHIGAN STATE UNIVERSITY, 1990.Source: Dissertation Abstracts International, Volume: 51-12, Section: B, page: 5
Other
1
Scientific paper
Relative populations of particle-unstable states were measured for complex fragments emitted in the reaction ^{rm 14}N + Ag at E/A = 35 MeV by using a position sensitive high resolution hodoscope. The hodoscope consisted of 13 telescopes, four of these telescopes were designed to isotopically resolve fragments with 3 <=q Z <=q 10 and the other nine to resolve hydrogen and helium isotopes. In order to optimize the excitation energy resolution of the hodoscope, each telescope contained an x - y position sensitive gas proportional counter. A position resolution better than 0.5 mm was obtained for 5.8 MeV alpha-particles. For the alpha-decay channels of the particle unstable ^{rm 10}B nucleus produced in the reaction, an excitation energy resolution of about 50 keV (FWHM) was achieved. Experimental population probabilities of particle -unstable states were extracted by fitting the coincidence spectra of the decay products by an appropriate R -matrix or Breit-Wigner formalism. According to thermal models, the populations of excited states at freezeout are expected to follow a Boltzmann distribution weighted by the emission temperature of the system. Tests of this freezeout assumption were made by comparing the experimental population to the predictions of statistical calculations. Extensive statistical calculations which include the effect of sequential feeding from heavier particle unstable nuclei were performed to estimate the population probabilities of the states starting with a thermal distribution of primary fragments at an initial temperature, T _{rm em}. A global comparison of the measured and calculated population probabilities and the ratios of population probabilities indicate emission temperatures of about 3-4 MeV. But a detailed comparison for individual fragments for a calculation with T _{rm em} =4 MeV reveals that about half of the measured population probabilities and one third of the ratios of the population probabilities differ significantly from the predictions of statistical calculations. Calculations which include rotational effects could not satisfactorily account for this discrepancy. These results suggest a possible breakdown of the assumption of local thermal equilibrium at freezeout.
No associations
LandOfFree
Emission Temperatures from the Decay of Particle - Complex Nuclei. does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Emission Temperatures from the Decay of Particle - Complex Nuclei., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Emission Temperatures from the Decay of Particle - Complex Nuclei. will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1564467