26795671
Coulomb excitation of cadmium isotopes with protons.
Low-lying positive parity levels of the isotopes in natural cadmium were Coulomb excited with 2.7--4.2 MeV protons. Eight levels of /sup 111/Cd up to 1130.4 keV and four levels of /sup 113/Cd up to 680.5 keV excitation energy, and the first 2/sup +/ states in even-even isotopes (/sup 110,112,114,116/Cd) were excited. A 50 cm/sup 3/ Ge(Li) detector was used to measure the deexcitation gamma-ray yields. The 1130.4 keV level in /sup 111/Cd had not been investigated earlier through Coulomb excitation. Also the 245.4, 700, 754.9, 855.6, and 1020.7 keV levels in /sup 111/Cd, and the 316.1 keV level in /sup 113/Cd were Coulomb excited with protons for the first time. The reduced E2 transition probabilities B(E2), and partial half-lives T/sub 1/2/ (E2), for various levels were determined. The gamma-ray angular distributions were analyzed to deduce the E2/M1 mixing ratios (delta) for various transitions from the levels in /sup 111,113/Cd. The 700, 754.9, 855.6, and 1020.7 keV levels in /sup 111/Cd, and the 680.5 keV level in /sup 113/Cd have been assigned a spin value of (3/2)/sup +/, while the 1130.4 keV level in /sup 111/Cd has been assigned a spin of (5/2)/sup +/. The results have been compared with existingmore » theoretical and experimental data in the literature.« less
120945477
On improvement of charge resolution of cosmic ray particles using a cellulose nitrate plastic detector
Abstract By employing improved procedures of measurement and analysis we have been able to obtain good charge resolution for stopping cosmic ray nuclei with Z ⩽30 in a cellulose nitrate detector. In a particular, it has been found that ( V t V b ) provides a much more reliable measure of ionisation loss than cone length. A charge resolution of 0.2 charge units for nuclei with Z ≲20 and of 0.3 charge units for nuclei with Z > 20 has been achieved in the present experiment.
122026076
Role of nuclear dissipation and entrance channel mass asymmetry in pre-scission neutron multiplicity enhancement in fusion-fission reactions
Pre-scission neutron multiplicities are measured for ${}^{12}\mathrm{C} + {}^{204}\mathrm{Pb}$ and ${}^{19}\mathrm{F} + {}^{197}\mathrm{Au}$ reactions at laboratory energies of 75\char21{}95 MeV for the $^{12}\mathrm{C}$ beam and 98\char21{}118 MeV for the $^{19}\mathrm{F}$ beam. The chosen projectile-target combinations in the present study lie on either side of the Businaro-Gallone mass asymmetry (${\ensuremath{\alpha}}_{\mathrm{BG}}$) and populate the $^{216}\mathrm{Ra}$ compound nucleus. The dissipation strength is deduced after comparing the experimentally measured neutron yield with the statistical model predictions which contains the nuclear viscosity as a free parameter. Present results demonstrate the combined effects of entrance channel mass asymmetry and the dissipative property of nuclear matter on the pre-scission neutron multiplicity in fusion-fission reactions.
120052850
Search for entrance channel effects in heavy ion induced fusion reactions through the compound system79Rb
120167461
Anomalous behavior of the level density parameter in neutron and charged particle evaporation
The compound nucleus $^{76}\mathrm{Kr}*$ was populated at the excitation energy of $75\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ and angular momentum of $39\ensuremath{\hbar}$ in fusion reactions with two complementary, mass-symmetric $(^{31}\mathrm{P}+^{45}\mathrm{Sc})$ and mass-asymmetric $(^{12}\mathrm{C}+^{64}\mathrm{Zn})$ entrance channels. The neutron evaporation spectra were measured and compared with the predictions of statistical model calculations using the transmission coefficients for the spherical nuclei in the inverse absorption channel, the rotating liquid drop model moment of inertia, and the normal systematic value of $A∕8$ for the level density parameter $a$. The results for the mass-asymmetric reaction are found to be consistent with the predictions of the statistical model calculations. However, for the mass-symmetric reaction $(^{31}\mathrm{P}+^{45}\mathrm{Sc})$, the experimental spectra are found to be harder than the theoretical neutron spectra and the statistical model calculations require a lower value of $A∕10$ for the parameter $a$ to reproduce the shape of the experimental spectra, indicating the neutron to be evaporated at higher temperature for the same excitation energy and angular momentum in symmetric system. According to the dynamical model, the formation time $(37\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}\phantom{\rule{0.3em}{0ex}}\mathrm{sec})$ of the compound nucleus for the symmetric $^{31}\mathrm{P}+^{45}\mathrm{Sc}$ system is significantly higher than that $(29\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}22}\phantom{\rule{0.3em}{0ex}}\mathrm{sec})$ for the asymmetric $^{12}\mathrm{C}+^{64}\mathrm{Zn}$ system. This may probably lead to the formation of a temperature-equilibrated dinuclear complex that may be responsible for neutron emission at higher temperature in the case of the symmetric system.
122194176
Search for entrance channel effects in heavy ion induced fusion reactions via neutron evaporation
40983341
Nucleus-nucleus multiplicity distributions and quantum chromodynamics.
A model for nucleus-nucleus multiplicity distributions is proposed and its relations with hadron-proton and hadron-nucleus multiplicity distributions are explored and compared with the experimental data. The values of the parameters are the same for all these processes and owe their origin to the quantum chromodynamical gluon bremsstrahlung mechanism. Some other consequences of the model are also analyzed and compared with the available experimental data.
22845460
Birkhoff's theorem for electromagnetic fields in a new scalar-tensor theory.
A result having formal similarity to Birkhoff's theorem in general relativity is proved in the presence of electromagnetic fields in a new scalar-tensor theory of gravitation proposed by Schmidt et al. for the special case when the scalar field is massless and independent of time.
28689431
Quantization of Nambu-Goto strings with new boundary conditions.
If a classical Nambu-Goto string in D dimensions is required to have Poincare invariance in d dimensions, d
36246455
The quasiopen string.
The quasiopen string in D dimensions is defined by the Nambu-Goto action and the boundary conditions (x'+x)(σ α ,τ)=V α (x'-x) (σ α ,τ), where σ=σ 1 and σ 2 denote the ends of the string, x'≡∂x/∂σ, and the V α (α=1,2) are real symmetric orthogonal matrices. (The usual open string corresponds to V 1 =V 2 =−1.) We impose Poincare invariance in d dimensions, d α ) jk =−δ jk for j,k ∈ Poincare sector and (V α ) jk =0 if only one of j,k belongs to the Poincare sector. Further quantization gives D=26 and a mass spectrum with a ground-state mass squared M G 2 =−(1−J i ||theta i ||(1-||theTa I ||)/4)/α', where ||theta i ||≤(½), exp(2iπtheta i ) are the eigenvalues of V 2 V 1 , and α' is the slope parameter in the string action. A choice of theta i giving a tachyon-free spectrum is thus possible if d≤10.
35249306
Quantum violation of stochastic noncontextual hidden-variable theories.
We formulate stochastic noncontextual hidden-variable theories. In such theories the hidden state λ specifies not definite values, but expectation values A − (λ), ... of observables A, ... and noncontextuality means that A − (λ) is independent of which other commuting observables commuting with A are measured together with A. We show via Bell inequalities that such theories conflict with quantum theory and propose a two-photon experimental test. We also show that for a single particle of spin (2 n −1)/2, quantum violation of classical noncontextuality grows exponentially with n.