Inverse bremsstrahlung is one important way to deliver laser energy to the plasma in inertial confinement fusion. In this article, we study the collisional absorption rate as obtained from the ...Fokker–Planck treatment of an unmagnetized plasma in harmonic laser field. The electron–ion collision rate is considered in the Krook approximation, and the electron distribution function is considered a Maxwellian function. We evaluate the inverse bremsstrahlung absorption near the irradiated plasma surface in the critical layer. We observe that absorption increases with shorter laser wavelength and lower electron temperatures. When the maximum electron velocity in the limit of q → 1 reaches infinity, the q‐non‐extensive distribution function reduces to the standard Maxwell‐Boltzmann distribution.
Inverse bremsstrahlung absorption (IBA) is the most efficient absorption mechanism in laser-fusion plasma. IBA is the process in which an electron absorbs a photon while colliding with an ion or with ...another electron. IBA of laser energy in homogeneous and unmagnetized plasma has been studied using the Fokker–Planck equation. The isotropic function is considered as a
q
-nonextensive electrons distribution function. By considering a circular-polarized laser, kinetic theory and spherical coordinates, the first anisotropic function is calculated. A pulsed laser is considered, and the effect of the physical parameters such as temperature and
q
(
q
is a parameter quantifying the degree of nonextensivity) has been studied on the absorption value. Later, the results of continuous laser and pulsed laser have been compared. The calculations of IBA performed for a variety of
q
. According to our calculations, the IBA value in neighboring of the critical density layer for continuous laser is higher than pulsed laser. The final results show the IBA value increases with increase in
q
parameter and oppositely it decreases with temperature increasing.
Abstract
The present study aimed to calculate the yields of DNA
breaks and the variation of relative biological effectiveness (RBE)
at different depths for protons using Geant4-DNA. For this purpose,
...an atomic model of DNA and a DNA damage classification matrix were
used to calculate different DNA break yields for 62-MeV protons. As
the reference radiation, the secondary electron spectrum produced by
60
Co was evaluated. This helped to calculate the SSB and DSB
yields. Moreover, RBE was found to be between 1.1 at the first point
and 1.51 in the Bragg peak region. In this region, it was 37%
greater than the 5-mm depth in the plateau region. Considering
different threshold energies, the energy deposition at 10.79 eV had
the most contribution to the total damage. As the results suggested,
the depth dependence of RBE should be taken into account for proton
therapy. It was also found that DNA break yields significantly
depend on the threshold energy value.
Vector-analyzing powers,
A
x
and
A
y
, of the proton–deuteron break-up reaction have been measured by using a polarized-proton beam at 135 MeV impinging on a liquid-deuterium target. For the ...experiment, the big instrument for nuclear-polarization analysis (BINA) was used at KVI, Groningen, the Netherlands. The data are compared to the predictions of Faddeev calculations using state-of-the-art two- and three-nucleon potentials. Our data are reasonably well described by calculations for the kinematical configurations at which the three-nucleon force (3NF) effect is predicted to be small. However, striking discrepancies are observed at specific configurations, in particular in the cases of symmetric configurations, where the relative azimuthal angle between the two protons is small which corresponds to the
d
(
p
→
,
2
He
)
n
channel. The vector-analyzing powers of these configurations are compared to the proton–deuteron elastic scattering to study the spin–isospin sensitivity of the 3NF models. The results are compared to the earlier results of the proton–deuteron break-up reaction at 190 MeV proton-beam energy
1
. Disagreement is observed for both proton-beam energies between data and calculations which points to a deficiency in the treatment of spin–isospin part of the 3NF.
A selection of measured cross sections and vector analyzing powers,
A
x
and
A
y
, are presented for the
p
→
d
break-up reaction. The data are taken with a polarized proton beam with a kinetic energy ...of 135 MeV using the Big Instrument for Nuclear-polarization Analysis (BINA) at KVI, the Netherlands. With this setup,
A
x
is extracted for the first time for a large range of energies as well as polar and azimuthal angles of the two outgoing protons. For most of the configurations, the results at small and large relative azimuthal angles differ in behavior when comparing experimental data with the theoretical calculations. We also performed a more global comparison of our data with theoretical calculations. The cross-section results show huge values of
χ
2
/d.o.f.. The absolute values of
χ
2
/d.o.f. for the components of vector analyzing powers,
A
x
and
A
y
, are smaller than the ones for the cross section, partly due to larger uncertainties for these observables. However, also for these observables no satisfactory agreement is found for all angular combinations. This implies that the present models of a three-nucleon force are not able to provide a satisfactory description of experimental data.
Detailed measurements of five-fold differential cross sections and a rich set of vector and tensor analyzing powers of the
2
H
(
d
,
d
p
)
n
break-up process using polarized deuteron-beam energy of ...65 MeV/nucleon with a liquid-deuterium target are presented. The experiment was conducted at the AGOR facility at KVI using the BINA 4
π
-detection system. We discuss the analysis procedure including a thorough study of the systematic uncertainties. The results can be used to examine upcoming state-of-the-art calculations in the four-nucleon scattering domain, and will, thereby, provide further insights into the dynamics of three- and four-nucleon forces in few-nucleon systems. The results of coplanar configurations are compared with the results of recent theoretical calculations based on the Single-Scattering Approximation (SSA). Through these comparisons, the validity of SSA approximation is investigated in the Quasi-Free (QF) region.
A measurement of the analyzing powers for the
2
H
(
p
→
,
p
p
)
n
break-up reaction was carried out at KVI exploiting a polarized-proton beam at an energy of
135
MeV
. The scattering angles and ...energies of the final-state protons were measured using the Big Instrument for Nuclear-polarization Analysis (BINA) with a nearly
4
π
geometrical acceptance. In this work, we analyzed a large number of kinematical geometries including forward–forward configurations in which both the final-state particles scatter to small polar angles and backward–forward configurations in which one of the final-state particles scatters to large polar angles. The results are compared with Faddeev calculations based on modern nucleon–nucleon (NN) and three-nucleon (3N) potentials. Discrepancies between polarization data and theoretical predictions are observed for configurations corresponding to small relative azimuthal angles between the two final-state protons. These configurations show a large sensitivity to 3N force effects.
We present measurements of differential cross sections and analyzing powers for the elastic
2
H
(
d
,
d
)
d
scattering process. The data were obtained using a 130 MeV polarized deuteron beam. Cross ...sections and spin observables of the elastic scattering process were measured at the AGOR facility at KVI using two independent setups, namely BINA and BBS. The data harvest at setups are in excellent agreement with each other and allowed us to carry out a thorough systematic analysis to provide the most accurate data in elastic deuteron-deuteron scattering at intermediate energies. The results can be used to confront upcoming state-of-the-art calculations in the four-nucleon scattering domain, and will, thereby, provide further insights in the dynamics of three- and four-nucleon forces in few-nucleon systems.
Understanding of the exact nature of three-nucleon forces is the most challenging topic in the field of nuclear physics. Three-nucleon break-up reaction is a good tool to look into the underlying ...dynamics of the nuclear force, thanks to its rich kinematical phase space which has different levels of sensitivity to three-nucleon force effects. The recent studies on few-nucleon systems have revealed that the current nuclear force models cannot describe nucleon-deuteron scattering data accurately. In the present work, the analyzing powers of the proton-deuteron break-up reaction obtained using a 190 MeV polarized proton beam will be discussed. We present for the first time the vector analyzing powers for the kinematics in which one of the protons scatters to intermediate and large scattering angles at this energy. The results show a fairly good agreement with various theoretical predictions for both intermediate and large scattering angles of the break-up phase space.
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