ENERGY SPECTRUM OF NEUTRONS FROM A THORIUM ACTIVE DEPOSIT – BERYLLIUM SOURCE

1951 ◽  
Vol 29 (2) ◽  
pp. 129-136 ◽  
Author(s):  
D. A. Bromley
Keyword(s):  
Angular Distribution ◽  
Energy Spectrum ◽  
Experimental Error ◽  
Energy Levels ◽  
Maximum Energy ◽  
Alpha Particles ◽  
Cloud Chamber

The energy spectrum of the neutrons emitted when beryllium is bombarded with alpha particles from Th (C + C′) has been determined by measuring the ranges and directions of recoil of protons produced in a cloud chamber by the neutrons. The maximum energy of the neutrons was found to be about 15.5 Mev., within experimental error of the calculated maximum, 14.4 Mev. Many neutrons were found with energy of about 2.15 Mev. and the structure in the remainder of the spectrum can be attributed to the existence of energy levels in C12 at about 7.1 and 4.5 Mev. The angular distribution of the protons scattered by the neutrons from this source was isotropic to within experimental error.

New Particles

2018 ◽  
Author(s):  
Roger H. Stuewer
Keyword(s):  
Gamma Rays ◽  
Atomic Hydrogen ◽  
Nuclear Physics ◽  
Hydrogen Isotope ◽  
Alpha Particles ◽  
Cloud Chamber ◽  
Ernest Rutherford ◽  
James Chadwick ◽  
Theoretical Foundations ◽  
New Particles

In December 1931, Harold Urey discovered deuterium (and its nucleus, the deuteron) by spectroscopically detecting the faint companion lines in the Balmer spectrum of atomic hydrogen that were produced by the heavy hydrogen isotope. In February 1932, James Chadwick, stimulated by the claim of the wife-and-husband team of Irène Curie and Frédéric Joliot that polonium alpha particles cause the emission of energetic gamma rays from beryllium, proved experimentally that not gamma rays but neutrons are emitted, thereby discovering the particle whose existence had been predicted a dozen years earlier by Chadwick’s mentor, Ernest Rutherford. In August 1932, Carl Anderson took a cloud-chamber photograph of a positron traversing a lead plate, unaware that Paul Dirac had predicted the existence of the anti-electron in 1931. These three new particles, the deuteron, neutron, and positron, were immediately incorporated into the experimental and theoretical foundations of nuclear physics.

Angular Distribution of Rotons Generated by Alpha Particles in Superfluid Helium: A Possible Tool for Low Energy Particle Detection

1995 ◽  
Vol 74 (16) ◽  
pp. 3169-3172 ◽  
Author(s):  
S. R. Bandler ◽  
S. M. Brouër ◽  
C. Enss ◽  
R. E. Lanou ◽  
H. J. Maris ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Superfluid Helium ◽  
Alpha Particles ◽  
Low Energy ◽  
Energy Particle ◽  
Particle Detection

scholarly journals Electron energy spectrum produced by stochastic acceleration in the laser–plasma interaction

2017 ◽  
Vol 35 (2) ◽  
pp. 265-273 ◽  
Author(s):  
E. Khalilzadeh ◽  
A. Chakhmachi ◽  
J. Yazdanpanah
Keyword(s):  
Energy Spectrum ◽  
Laser Pulse ◽  
Rise Time ◽  
Wave Breaking ◽  
Boundary Effect ◽  
Maximum Energy ◽  
Intense Laser ◽  
Stochastic Acceleration ◽  
Direct Laser ◽  
Short Rise Time

AbstractIn this paper, the electrons energy spectrum produced by stochastic acceleration in the interaction of an intense laser pulse with the underdense plasma is described by employing the fully kinetic 1D-3 V particle-in-cell simulation. In this way, two finite laser pulses with the same length 200 fs and with two different rise times 30 and 60 fs are typically selected. It is shown that the maximum energy of electrons in the laser pulse with the short rise time (30 fs) is about eight times greater than the maximum energy of the electrons with the long rise time (60 fs). Furthermore, unlike the pulse with the short rise time, the shape of energy spectrum and the electrons temperature in the long rise time laser pulse are approximately unchanged over the time. These results originated from the fact that in the case of long rise time laser pulse, all electrons are accelerated by the one chaotic mechanism because of the scattered fields generated in the plasma, but in the case of short rise time laser pulse, three different mechanisms accelerate the electrons: first, the stochastic acceleration because of the nonlinear wave breaking via plasma-vacuum boundary effect; second, the stochastic acceleration initiated by the wave breaking; and third, the direct laser acceleration of the released electrons.

ALPHA DECAY AND FISSION OF ALIGNED NUCLEI

1960 ◽  
Vol 38 (2) ◽  
pp. 290-314 ◽  
Author(s):  
N. R. Steenberg ◽  
R. C. Sharma
Keyword(s):  
Angular Distribution ◽  
High Temperature ◽  
Experimental Work ◽  
Low Temperatures ◽  
Alpha Decay ◽  
Alpha Particles ◽  
Nuclear Shape ◽  
Fission Fragments ◽  
Partial Waves ◽  
High Temperature Approximation

The theory of the angular distribution of alpha particles and of fission fragments from nuclei aligned at low temperatures is presented. Very explicit results are obtained in the high temperature approximation. These are directly dependent upon the branching which takes place to the various allowed partial waves. This branching is influenced by the nuclear shape, but it is shown that for this problem the effect of penetrating a spheroidal barrier is not critical. An application is made to the experimental work so far available and the result is reasonably satisfactory.

scholarly journals A Study of The Alpha – Nucleus Scattering

2014 ◽  
Vol 40 (2) ◽  
pp. 249-258
Author(s):  
DR Sarker ◽  
Ain Ul Huda ◽  
SK Das ◽  
Md K Hasan ◽  
Md M Parvej ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Alpha Particles ◽  
Strong Absorption ◽  
Distribution Data ◽  
Absorption Model ◽  
Angular Range ◽  
Deformation Parameters ◽  
Nucleus Scattering ◽  
Best Fit ◽  
Collective States

Angular distribution data for the elastic scattering of 1.37 GeV alpha particles from several nuclei are analyzed in terms of the three parameter strong absorption model of Frahn and Venter. The fits are quite satisfactory over practically the entire angular range and the best fit parameters are obtained. These are used for the study of the inelastic scattering of alpha particles leading to the collective states in nuclei. A reasonably good fit is obtained without any adjustment of the parameters suggesting thereby the success of the strong absorption model. Deformation parameters are extracted for the collective states in nuclei. Asiat. Soc. Bangladesh, Sci. 40(2): 249-258, December 2014

scholarly journals Observation of ultra-fine structures in energy levels of prolate nuclei

2018 ◽  
Vol 96 (9) ◽  
pp. 1059-1062 ◽  
Author(s):  
Hassan Hassanabadi ◽  
Hadi Sobhani
Keyword(s):  
Energy Spectrum ◽  
Commutation Relation ◽  
Atomic Physics ◽  
Nuclear Physics ◽  
Energy Levels ◽  
Zeeman Effect ◽  
Three Dimensions ◽  
Energy Splitting ◽  
Commutation Relations ◽  
Fine Structures

This work discusses the observation of splitting in the energy levels of prolate nuclei. Similar effects in atomic physics are known as the Zeeman effect, but in nuclear physics the feasibility of such phenomena has not been observed. After introducing a deformation in the commutation relation in three dimensions, we used these commutation relations in X(3) model. After enough derivation, we then evaluate the energy spectrum relation for the considered system, which has resulted in energy splitting. With these observations in the energy splitting we referred to such an effect as the ultra-fine structures in energy levels. At the end some plots have been depicted to illustrate the results.

Shape coexistence in $^{76}$Se within the neutron-proton interacting boson model

2021 ◽  
Author(s):  
Chengfu Mu ◽  
Dali Zhang
Keyword(s):  
Experimental Data ◽  
Energy Spectrum ◽  
Excitation Energy ◽  
Energy Levels ◽  
Spherical Shape ◽  
Interacting Boson Model ◽  
Shape Coexistence ◽  
Electromagnetic Transition ◽  
Boson Model ◽  
Good Agreement

Abstract We have investigated the low-lying energy spectrum and electromagnetic transition strengths in even-even $^{76}$Se using the proton-neutron interacting boson model (IBM-2). The theoretical calculation for the energy levels and $E2$ and $M1$ transition strengths is in good agreement with the experimental data. Especially, the excitation energy and $E2$ transition of $0^+_2$ state, which is intimately associated with shape coexistence, can be well reproduced. The analysis on low-lying states and some key structure indicators indicates that there is a coexistence between spherical shape and $\gamma$-soft shape in $^{76}$Se.

The Fermi Level

2020 ◽  
pp. 267-300
Author(s):  
Brian Cantor
Keyword(s):  
Fermi Level ◽  
Atomic Bomb ◽  
Energy Levels ◽  
Pauli Exclusion Principle ◽  
Mean Free Path ◽  
Maximum Energy ◽  
Exclusion Principle ◽  
Energy Bands ◽  
Anti Semitism ◽  
Dielectric Effect

The Fermi level is the maximum energy of the electrons in a material. Effectively there is a Fermi equation: EF = E max. This chapter examines the discrete electron energy levels in individual atoms as a consequence of the Pauli exclusion principle, the corresponding energy bands in a material composed of many atoms or molecules, and the way in which conductor, insulator and semiconductor materials depend on the position of the Fermi level relative to the energy bands. It explains: the concepts of electron mobility, mean free path and conductivity; the dielectric effect and capacitance; p-type, n-type, intrinsic and extrinsic semiconductors; and the behaviour of some simple microelectronic devices. Enrico Fermi was the son of a minor railway official in Rome. He had a meteoric scientific career in Italy, developing Fermi-Dirac statistics for the energies of fundamental fermion particles (such as electrons and protons), discovering the neutrino, and explaining the behaviour of different materials under bombardment from fast and slow neutrons. After initially joining Mussolini’s Fascist Party, he became unhappy at the level of anti-Semitism (his wife was Jewish) and left suddenly for America, immediately after receiving the Nobel Prize in Sweden. At Columbia and Chicago Universities and at Los Alamos National Labs, he played a key scientific role in developing controlled fission in an atomic pile, leading to the development of the atomic bomb towards the end of the Second World War, and the nuclear energy industry after the war.

scholarly journals Effects of Compton scattering on the neutron star radius constraints in rotation-powered millisecond pulsars

2019 ◽  
Vol 627 ◽  
pp. A39 ◽  
Author(s):  
Tuomo Salmi ◽  
Valery F. Suleimanov ◽  
Juri Poutanen
Keyword(s):  
Angular Distribution ◽  
Neutron Star ◽  
Energy Spectrum ◽  
Compton Scattering ◽  
Electron Scattering ◽  
Exact Formulation ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Synthetic Phase ◽  
Neutron Star Radius

The aim of this work is to study the possible effects and biases on the radius constraints for rotation-powered millisecond pulsars when using Thomson approximation to describe electron scattering in the atmosphere models, instead of using exact formulation for Compton scattering. We compare the differences between the two models in the energy spectrum and angular distribution of the emitted radiation. We also analyse a self-generated, synthetic, phase-resolved energy spectrum, based on Compton atmosphere and the most X-ray luminous, rotation-powered millisecond pulsars observed by the Neutron star Interior Composition ExploreR (NICER). We derive constraints for the neutron star parameters using both the Compton and Thomson models. The results show that the method works by reproducing the correct parameters with the Compton model. However, biases are found in both the size and the temperature of the emitting hotspot, when using the Thomson model. The constraints on the radius are still not significantly changed, and therefore the Thomson model seems to be adequate if we are interested only in the radius measurements using NICER.

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