In this paper the improved multipolar model of bremsstrahlung accompanied the $α$-decay is presented. The angular formalism of calculations of the matrix elements, being enough complicated component of the model, is stated in details. A new definition of the angular (differential) probability of the photon emission in the $α$-decay is proposed where direction of motion of the $α$-particle outside (with its tunneling inside barrier) is defined on the basis of angular distribution of its spacial wave function. In such approach, the model gives values of the angular probability of the photons emission in absolute scale, without its normalization on experimental data. Effectiveness of the proposed definition and accuracy of the spectra calculations of the bremsstrahlung spectra are analyzed in their comparison with experimental data for the $^{210}{\rm Po}$, $^{214}{\rm Po}$, $^{226}{\rm Ra}$ and $^{244}{\rm Cm}$ nuclei, and for some other nuclei predictions are performed (in absolute scale). With a purpose to find characteristics taking influence on the bremsstrahlung probability strongly, a dependence of the bremsstrahlung probability on effective charge of the decaying system is analyzed. As a natural result, as supposed type of decaying system the emission of proton from nucleus is studied, for which the effective charge is essentially larger in a comparison with $α$-decay. For some proton emitters estimations of the bremsstrahlung probability are obtained (at first time, in fully quantum approach). Also the bremsstrahlung in fission of the $^{252}{\rm Cf}$ nucleus is analyzed.
Emission of bremsstrahlung photons accompanying proton decay of nuclei is studied. The new improved multipolar model describing such a process is presented. The angular formalism of calculations of the matrix elements is stated in details. The bremsstrahlung probabilities for the $^{157}{\rm Ta}$, $^{161}{\rm Re}$, $^{167}{\rm Ir}$ and $^{185}{\rm Bi}$ nuclei decaying from the $2s_{1/2}$ state, the $^{109}_{53}{\rm I}_{56}$ and $^{112}_{55}{\rm Cs}_{57}$ nuclei decaying from the $1d_{5/2}$ state, the $^{146}_{69}{\rm Tm}_{77}$ and $^{151}_{71}{\rm Lu}_{80}$ nuclei decaying from the $0h_{11/2}$…
Model of angular bremsstrahlung of photons emitted during $α$-decay is presented. A special emphasis is given on development of unified formalism of matrix elements in the dipole and multipolar approaches. A probability of the emission of photons calculated on the basis of the multipole model without any normalization on experimental data (i. e. in absolute scale) is found at $90^{\circ}$ of the angle $\vartheta_{αγ}$ between directions of motion of the $α$-particle (with its tunneling under barrier) and emission of photons to be in a good agreement with the newest experimental data for the $^…
We analyze if the nucleon structure of the $α$ decaying nucleus can be visible in the experimental bremsstrahlung spectra of the emitted photons which accompany such a decay. We develop a new formalism of the bremsstrahlung model taking into account distribution of nucleons in the $α$ decaying nuclear system. We conclude the following: (1) After inclusion of the nucleon structure into the model the calculated bremsstrahlung spectrum is changed very slowly for a majority of the $α$ decaying nuclei. However, we have observed that visible changes really exist for the $^{106}{\rm Te}$ nucleus ($Q_…
A new quantum electrodynamical method of calculations of bremsstrahlung spectra in the $α$-decay of heavy nuclei taking into account the angle between the directions of $α$-particle motion (or its tunneling) and photon emission is presented. The angular bremsstrahlung spectra for $^{210}{Po}$ have been obtained for the first time. According to calculations, the bremsstrahlung in the $α$-decay of this nucleus depends extremely weakly on the angle. Taking into account nuclear forces, such dependence is not changed visibly. An analytical formula of the angular dependence of the bremsstrahlung spe…
A quantum mechanical model for the description of the alpha-decay of heavy nuclei with accompanying photons emission is presented. The model is based on a quantum mechanical one-particle model of alpha-decay through a decay barrier. The bremsstrahlung spectrum calculation employs multipole expansion of the vector potential of the Coulomb field of the daughter nucleus and takes into account the dependence on the angle between the directions of the alpha-particle propagation and the photon emission. Spectra of 210Po are obtained for the angles 25 and 90, and the best agreement with the experimen…
A high-statistics measurement of bremsstrahlung emitted in the alpha decay of 210Po has been performed, which allows to follow the photon spectra up to energies of ~ 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasi classical approximation as well as with the exact quantum mechanical calculation. It is shown that due to the small effective electric dipole charge of the radiating system a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the a…
We investigate possibility of emission of the bremsstrahlung photons in nuclear reactions with hypernuclei for the first time. A new model of the bremsstrahlung emission which accompanies interactions between $α$ particles and hypernuclei is constructed, where a new formalism for the magnetic momenta of nucleons and hyperon inside hypernucleus is added. For first calculations, we choose $α$ decay of the normal nucleus $^{210}{\rm Po}$ and the hypernucleus $^{211}_Λ{\rm Po}$. We find that (1) emission for the hypernucleus $^{211}_Λ{\rm Po}$ is larger than for normal nucleus $^{210}{\rm Po}$, (2…
A quantum mechanical method of calculation of bremsstrahlung spectra in alpha-decay of heavy nuclei with taking into account an angle between directions of the alpha-particle motion and the photon emission is presented. Dependence between the bremsstrahlung spectrum and the angle value is obtained in a simple analytical form. The method can be used for a comparative analysis of experimental data, obtained at different angles.
Using our previous approach to electromagnetic emission during tunneling, an explicit, essentially classical, formula describing the bremsstrahlung spectrum in alpha decay is derived. The role of tunneling motion in photon emission is discussed. The shape of the spectrum is a universal function of the ratio Eg/Eo , where Eg is the photon energy and Eo is a characteristic energy depending only on the nuclear charge and the energy of the alpha particle.
A quantum mechanical analysis of the bremsstrahlung in $α$ decay of $^{210}$Po is performed in close reference to a semiclassical theory. We clarify the contribution from the tunneling, mixed, outside barrier regions and from the wall of the inner potential well to the final spectral distribution, and discuss their interplay. We also comment on the validity of semiclassical calculations, and the possibility to eliminate the ambiguity in the nuclear potential between the alpha particle and daughter nucleus using the bremsstrahlung spectrum.
A semi-classical model based on quantum time concepts is presented for the evaluation of bremsstrahlung emission probabilities in alpha decay of nuclei. The contribution to the bremsstrahlung emission from the different regions in tunneling is investigated using realistic double folded nuclear and Coulomb potentials. Within this model, the contribution from the radiation emitted in front of the barrier before tunneling is much larger than that while leaving the barrier. A comparison with the data on $^{210}$Po shows that the results are sensitive to the nuclear potential and the rectangular we…
We present the first fully quantum mechanical calculation of photon radiation accompanying charged particle decay from a barrier resonance. The soft-photon limit agrees with the classical results, but differences appear at next-to-leading-order. Under the conditions of alpha-decay of heavy nuclei, the main contribution to the photon emission stems from Coulomb acceleration and may be computed analytically. We find only a small contribution from the tunneling wave function under the barrier.
We present a quasiclassical theory of alpha decay accompanied by bremsstrahlung with a special emphasis on the case of 210Po, with the aim of finding a unified description that incorporates both the radiation during the tunneling through the Coulomb wall and the finite energy E_gamma of the radiated photon up to E_gamma on the order of Q_alpha/sqrt(eta), where Q_alpha is the alpha-decay Q-value and eta is the Sommerfeld parameter. The corrections with respect to previous quasiclassical investigations are found to be substantial, and excellent agreement with a full quantum mechanical treatment …
We study the bremsstrahlung radiation of a tunneling charged particle in a time-dependent picture. In particular, we treat the case of bremsstrahlung during alpha-decay, which has been suggested as a promissing tool to investigate the problem of tunneling times. We show deviations of the numerical results from the semiclassical estimates. A standard assumption of a preformed particle inside the well leads to sharp high-frequency lines in the bremsstrahlung emission. These lines correspond to "quantum beats" of the internal part of the wavefunction during tunneling arising from the interference…
The two neutrino and neutrinoless double beta decay of $^{94,96}$Zr, $^{98,100}$Mo, $^{104}$Ru, $^{110}$Pd, $^{128,130}$Te and $^{150}$Nd isotopes for the $0^{+}\to 0^{+}$ transition is studied within the PHFB framework along with an effective two-body interaction consisting of pairing, quadrupole-quadrupole and hexadecapole-hexadecapole correlations. It is found that the effect of hexadecapolar correlations can be assimilated substantially as a renormalization of the quadrupole-quadrupole interaction. The effect of deformation on nuclear transition matrix elements is investigated by varying t…
Within a covariant effective one-boson exchange model for the $T$ matrix of $NN$ interactions we present detailed calculations of bremsstrahlung cross sections for proton - proton and proton - neutron reactions at beam energies in the 1 GeV region. Besides pure bremsstrahlung processes we consider photons from $Δ$ decays and contributions from the $η\to γγ$ process. At beam energies above 700 MeV the $Δ$ decay channel dominates the spectra at large photon energies, where the interference between non-resonance processes and the $Δ$ decay channel becomes also important. Low energy photons stem f…
A new model of the bremsstrahlung emission which accompanies proton decay and collisions of protons off nuclei in the energy region from the lowest up to intermediate, has been developed. This model includes spin formalism, potential approach for description of interaction between protons and nuclei, and operator of emission includes component of the magnetic emission (defined on the basis of Pauli equation). In the problem of the bremsstrahlung during the proton decay in the first time a role of the magnetic emission is studied using such a model. For the studied $^{146}{\rm Tm}$ nucleus it h…
Thermal photon emission rates from hot hadronic matter are studied to order $e^{2}g^{4}$, where $g$ indicates a strong-interaction coupling constant. Radiative decay of mesons, Compton and annihilation processes for hadrons, and bremsstrahlung reactions are all considered. Compared to the standard rates from the literature, one finds two orders of magnitude increase for low photon energies stemming mainly from bremsstrahlung and then a modest increase (factor of 2) for intermediate and high energy photons owing to radiative decays for a variety of mesons and from other reactions involving stra…
We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average $\barν_e$ and $\barν_x$ $(x = μ, τ)$ energies, for this process with those for $e^{\pm}$ pair annihilation, plasmon decay, and photo-neutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas wide…
The low $p_T$ direct photon production from a variety of the hadronic sources is studied within the microscopic HSD transport approach for p+C, p+Pb and Pb+Pb collisions at 160 A GeV. The direct photon emission from elementary hadronic scatterings as well as meson-meson bremsstrahlung are incorporated. The influence of in-medium effects such as a collisional broadening of the vector-meson spectral functions on the photon emission rate is found to be hardly observable in the final spectra which are dominated by bremsstrahlung type processes. The uncertainties in the subtraction of the 'backgrou…
