Photodissociation Dynamics of Ortho and Meta Fluorophenols: The Origin of Fast Protons

A recent experimental study with time-resolved velocity map imaging demonstrated that the total kinetic energy release spectra obtained from photodissociation of <i>ortho</i> and <i>meta</i> fluorophenols have distinct features after excitation into the origin of the S₁ state. A peak at 6000 cm^-1 was observed for both molecules, while another at 13000 cm^-1dominates the spectrum of <i>ortho</i>-fluorophenol. The peak at 6000 cm^‑1 was assigned to H tunneling. Nevertheless, the 13000 cm^-1 feature remains unassigned. In this work, we performed a theoretical analysis, investigating two hypotheses for explaining the 13000 cm^‑1 signal. The first hypothesis is that it is due to one-photon absorption followed by ionization through resonant multiphoton dissociation. The second hypothesis is that the signal is due to two-photon absorption into a superexcited state, which dissociates yielding an H atom. We discuss the pros and cons of each hypothesis, laying the groundwork for future experiments.

Photodissociation Dynamics of Ortho and Meta Fluorophenols: The Origin of Fast Protons

A recent experimental study with time-resolved velocity map imaging demonstrated that the total kinetic energy release spectra obtained from photodissociation of <i>ortho</i> and <i>meta</i> fluorophenols have distinct features after excitation into the origin of the S₁ state. A peak at 6000 cm^-1 was observed for both molecules, while another at 13000 cm^-1dominates the spectrum of <i>ortho</i>-fluorophenol. The peak at 6000 cm^‑1 was assigned to H tunneling. Nevertheless, the 13000 cm^-1 feature remains unassigned. In this work, we performed a theoretical analysis, investigating two hypotheses for explaining the 13000 cm^‑1 signal. The first hypothesis is that it is due to one-photon absorption followed by ionization through resonant multiphoton dissociation. The second hypothesis is that the signal is due to two-photon absorption into a superexcited state, which dissociates yielding an H atom. We discuss the pros and cons of each hypothesis, laying the groundwork for future experiments.

Photodissociation Dynamics of Ortho and Meta Fluorophenols: The Origin of the Fast Protons

A recent experimental study with time-resolved velocity map imaging demonstrated that the total kinetic energy release spectra obtained from photodissociation of <i>ortho</i> and <i>meta</i> fluorophenols have distinct features after excitation into the origin of the S₁ state. A peak at 6000 cm^-1 was observed for both molecules, while another at 13000 cm^-1dominates the spectrum of <i>ortho</i>-fluorophenol. The peak at 6000 cm^‑1 was assigned to H tunneling. Nevertheless, the 13000 cm^-1 feature remains unassigned. In this work, we performed a theoretical analysis, investigating two hypotheses for explaining the 13000 cm^‑1 signal. The first hypothesis is that it is due to one-photon absorption followed by ionization through resonant multiphoton dissociation. The second hypothesis is that the signal is due to two-photon absorption into a superexcited state, which dissociates yielding an H atom. We discuss the pros and cons of each hypothesis, laying the groundwork for future experiments.

Pseudorapidity distributions of fast target protons in 32S-Em collisions at Dubna energy

In this paper, the possible mechanisms, which are responsible for the production of fast target fragments (gray particles with energy 26 up to 400[Formula: see text]MeV) that were emitted from the interactions of [Formula: see text]S nucleus with emulsion nuclei at energy 3.7[Formula: see text]A[Formula: see text]GeV, are studied by the pseudorapidity distribution. The angular distribution of the fast protons ([Formula: see text]-particles) emitted in the interactions of [Formula: see text]S-Em at 3.7[Formula: see text]A[Formula: see text]GeV is nicely described by exp (0.96 cos [Formula: see text], which was observed in proton-induced interactions up to incident energies of 800[Formula: see text]GeV. The pseudorapidity distributions of the produced [Formula: see text]-particles were investigated in order to study the characteristics of the emitted system of [Formula: see text]-particles for different target sizes (CNO, Em and AgBr groups of events). In all cases, the pseudorapidity distributions were parametrized using Gaussian fits. The temperature of the system emitting [Formula: see text]-particles (hot system) is predicated in the light of the proposed statistical model to be [Formula: see text][Formula: see text]MeV.

Fast and slow target proton production induced by the interactions of 22Ne and 24Mg projectiles with the heavy emulsion nuclei at Dubna energy

In this work, a detailed study on the multiplicity characteristics of fast and slow target protons produced in the interactions of 3.3A[Formula: see text]GeV [Formula: see text] and 3.7A[Formula: see text]GeV [Formula: see text]Mg projectiles with the heavy emulsion nuclei (AgBr) is performed. The experimental data of the multiplicity distributions (MDs) of gray (fast protons) and black (slow protons) particles are fitted with the negative binomial and Gaussian distributions indicating a reasonable consensus with each. The validity of scaling hypothesis of MDs of gray and black particles is verified by studying two types of scaling functions, Koba–Nielson–Olsen (KNO) scaling and Hegyi scaling. The experimental data are displayed by a simplified universal function in each scaling. An examination of the relationship between the entropy and the average multiplicity is performed. The measurements of the higher-order moments (mean, variance, skewedness and kurtosis) of MDs of proton target fragments are measured. The second Muller moments are calculated as well to investigate the correlation among the fast and slow target protons.

Neutrino Emission from Magnetized Microquasar Jets

The hadronic jets in a microquasar stellar system are modeled with the relativistic hydrocode PLUTO. We focus on neutrino emission from such jets produced by fast proton (nonthermal) collisions on thermal ones within the hadronic jet. We adopt a semianalytical approximation for the description of the secondary particles produced from p-p collisions and develop appropriate algorithms using the aforementioned injected protons as input. As a concrete example, we consider the SS-433 X-ray binary system for which several observations have been made the last decades. In contrast to the preset distribution of the fast protons along the jet employed in our previous works, in the present paper, we simulated it by using a power-law fast proton distribution along the PLUTO hydrocode. This distribution gradually sweeps aside the surrounding winds, during the jet advance through the computational grid. As a first step, in the present work, the neutrino energy spectrum is extracted from the model jet, facilitating a range of potential dynamical simulations in currently interesting microquasar jet systems.

Proton imaging of 3D density distribution for dense DT plasmas using regularization method

Three-dimensional (3D) density distribution of inhomogeneous dense deuterium tritium plasmas in laser fusion is revealed by the energy loss of fast protons going through the plasmas. The fast protons generated in the laser–plasma interaction can be used for the simulation of a plasma density diagnostics. The large linear and ill-posed equation set of the densities of all grids is obtained and then solved by the Tikhonov regularization method after dividing a 3D area into grids and knowing the initial and final energies of the protons. 3D density reconstructions with six proton sources are done without and with random noises added to the final energy. The revealed density is a little smaller than the simulated one in most simulated zones and the error is as much as those of 2D reconstructions with four proton sources. The picture element N is chosen as 2744 with consideration of smoothness and calculation memory of the computers. With fast calculation speed and low error, the Tikhonov regularization method is more suitable for 3D density reconstructions with large calculation amount than simultaneous iterative reconstruction method. Also the analytical expressions between the errors and the noises are established. Furthermore, the density reconstruction method in this paper is particularly suitable for plasmas with small density gradient. The errors without noises and with 2% noises added to the final proton energies are 3 and 20%, respectively, for the homogeneous plasma.