1,588 research outputs found
Isotopic composition of fragments in multifragmentation of very large nuclear systems: effects of the chemical equilibrium
Studies on the isospin of fragments resulting from the disassembly of highly
excited large thermal-like nuclear emitting sources, formed in the ^{197}Au +
^{197}Au reaction at 35 MeV/nucleon beam energy, are presented. Two different
decay systems (the quasiprojectile formed in midperipheral reactions and the
unique source coming from the incomplete fusion of projectile and target in the
most central collisions) were considered; these emitting sources have the same
initial N/Z ratio and excitation energy (E^* ~= 5--6 MeV/nucleon), but
different size. Their charge yields and isotopic content of the fragments show
different distributions. It is observed that the neutron content of
intermediate mass fragments increases with the size of the source. These
evidences are consistent with chemical equilibrium reached in the systems. This
fact is confirmed by the analysis with the statistical multifragmentation
model.Comment: 9 pages, 4 ps figure
Critical Temperature for the Nuclear Liquid-Gas Phase Transition
The charge distribution of the intermediate mass fragments produced in p (8.1
GeV) + Au collisions is analyzed in the framework of the statistical
multifragmentation model with the critical temperature for the nuclear
liquid-gas phase transition as a free parameter. It is found that
MeV (90% CL).Comment: 4 pages, 3 figures, published in Phys. Rev.
Experimental Signals of Phase Transition
The connection between the thermodynamics of charged finite nuclear systems
and the asymptotically measured partitions is presented. Some open questions,
concerning in particular equilibrium partitions are discussed. We show a
detailed comparison of the decay patterns in Au+ C,Cu,Au central collisions and
in Au quasi-projectile events. Observation of abnormally large fluctuations in
carefully selected samples of data is reported as an indication of a first
order phase transition (negative heat capacity) in the nuclear equation of
state.Comment: 8 pages, 8th International Conference on Nucleus-Nucleus Collisions,
Moscow 200
Protein kinase D enzymes are dispensable for proliferation, survival and antigen receptor-regulated NFκB activity in vertebrate B-cells
To investigate the importance of protein kinase D (PKD) enzymes we generated a PKD-null DT40 B-lymphocyte cell line. Previously we have shown that PKDs have an essential role in regulating class II histone deacetylases in DT40 B-cells [Matthews, S.A., Liu, P., Spitaler, M., Olson, E.N., McKinsey, T.A., Cantrell, D.A. and Scharenberg, A.M. (2006) Essential role for protein kinase D family kinases in the regulation of class II histone deacetylases in B lymphocytes. Mol. Cell Biol. 26, 1569–1577]. We now show that PKDs are also required to regulate HSP27 phosphorylation in DT40 B-cells. However, in contrast to previous observations in other cell types, PKD enzymes do not regulate basic cellular processes such as proliferation or survival responses, nor NFκB transcriptional activity downstream of the B cell antigen receptor. Thus, PKDs have a selective role in DT40 B-cell biology
Antideuteron yield at the AGS and coalescence implications
We present Experiment 864's measurement of invariant antideuteron yields in
11.5A GeV/c Au + Pt collisions. The analysis includes 250 million triggers
representing 14 billion 10% central interactions sampled for events with high
mass candidates. We find (1/2 pi pt) d^(2)N/dydpt = 3.5 +/- 1.5 (stat.)
+0.9,-0.5 (sys.) x 10^(-8) GeV^(-2)c^(2) for 1.8=0.35 GeV/c
(y(cm)=1.6) and 3.7 +/- 2.7 (stat.) +1.4,-1.5 (sys.) x 10^(-8) GeV^(-2)c^(2)
for 1.4=0.26 GeV/c, and a coalescence parameter B2-bar of 4.1 +/-
2.9 (stat.) +2.3,-2.4 (sys.) x 10^(-3) GeV^(2)c^(-3). Implications for the
coalescence model and antimatter annihilation are discussed.Comment: 8 pages, 4 figures, Latex, submitted to Phys. Rev. Let
Comparison of Source Images for protons, 's and 's in 6 AGeV Au+Au collisions
Source images are extracted from two-particle correlations constructed from
strange and non-strange hadrons produced in 6 AGeV Au + Au collisions. Very
different source images result from pp vs p vs
correlations. These observations suggest important differences in the
space-time emission histories for protons, pions and neutral strange baryons
produced in the same events
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