Shape Of Beta Spectrum Research Articles

Shape of the 935 keV beta transition of143Pr

The beta spectrum shape of the 7/2+ → 7/2− beta transition in the decay of143Pr is measured employing a thoroughly tested intermediate image beta ray spectrometer of the Siegbahn-Slatis type and using the source produced by irradiation of highly enriched stable142Ce sample. The spectrum exhibits a definite energy dependence and is well fitted with shape factorC(W) = 1 − (0·057 ± 0·006)W whereW is in m0c2 units for an end point energy of 935 ± 2 keV agreeing well with the results of Hamiltonet al and Spejweskiet al and disagreeing with the results of Persson and Reynolds. The single particle configurations for the low lying levels of143Pr could not give quantitative results.

Nilsson orbits for a particle in a woods-Saxon potential with Y02 and Y04 deformations, and coupled to core rotational states

Several searches for Beyond Standard Model physics rely on an accurate and highly precise theoretical description of the allowed β spectrum. Following recent theoretical advances, a C++ implementation of an analytical description of the allowed beta spectrum shape was constructed. It implements all known corrections required to give a theoretical description accurate to a few parts in 104. The remaining nuclear structure-sensitive input can optionally be calculated in an extreme single-particle approximation with a variety of nuclear potentials, or obtained through an interface with more state-of-the-art computations. Due to its relevance in modern neutrino physics, the corresponding (anti)neutrino spectra are readily available with appropriate radiative corrections. In the interest of user-friendliness, a graphical interface was developed in Python with a coupling to a variety of nuclear databases. We present several test cases and illustrate potential usage of the code. Our work can be used as the foundation for current and future high-precision experiments related to the beta decay process.Source code: https://github.com/leenderthayen/BSGDocumentation: http://bsg.readthedocs.ioProgram Title: BSGProgram Files doi: http://dx.doi.org/10.17632/gx6yrpn22x.1Licensing provisions: MITProgramming language: C++ and PythonNature of problem: The theoretical allowed β spectrum contains a large variety of corrections from different areas of physics, each of which is important in certain energy ranges. A high precision description is required for new physics searches throughout the entire nuclear chart.Solution method: We implement the analytical corrections described in recent theoretical work. Nuclear matrix elements in allowed Gamow–Teller β decay are calculated in a spherical harmonic oscillator basis. Wave functions can be calculated in an extreme single-particle approximation using different nuclear potentials, or provided by the user as the output from more sophisticated routines. Corresponding neutrino spectra are calculated with appropriate radiative corrections. A graphical user interface written in Python additionally provides connections to a variety of nuclear databases.Additional comments: CPC Library subprograms used: ABOV_v1_0

Measurement of the beta spectrum shape of 89Sr

The spectrum shape of the first-forbidden unique β-decay of 89Sr was measured with the high-resolution π 2 magnetic spectrometer of the TRISTAN on-line isotope separator system. The μ-spectrum shape was analysed using the electron radial wave functions (ERWF) tabulation of Bhalla and Rose. A method is presented for accurate linear interpolation of tabulated ERWF which includes corrections for screening by atomic electrons. The observed deviation from the theoretical first-forbidden unique spectrum shape can be represented by a shape correction factor 1+ b W with b = 0.049 ± 0.007. The end-point energy was found to be 1.488 ± 0.004 MeV.

Influence of hysteresis on shape factor measurements with a double focusing iron betaspectrometer

The reliability of a double focusing iron betaspectrometer for the measurement of the shape of beta spectra has been investigated. The method used to estimate the influence of a charge in the magnetic state of the iron on the transmission is described. The results of this method applied to our spectrometer together with the experiments to test these results are given.

Shape factor and directional correlation measurements in the first-forbidden beta decay of 139Ba

The beta-spectrum shape factor and the beta-gamma directional correlation of the 7/2−(β)5/2 +2(γ)7/2 +2 cascade in the decay of 139Ba have been measured as a function of the beta-particle energy. Values of the four nuclear matrix elements of the beta-decay Hamiltonian are obtained from at least-squares fitting of the experimental data to the “exact” theoretical formalism, which implies numerical calculation of the electron wave function, including nuclear finite size and' finite de Brodlie wavelength effects. The experimental values of these matrix elements are compared to a theoretical evaluation on the basis of the j-j coupling model.

Beta-spectrum shape measurements with a 4π semiconductor spectrometer

A 4π semiconductor spectrometer employing diffused window lithium-drifted silicon detectors has been constructed. It was tested by varying the parameters of the system, so as to eliminate possible sources of distortion. It was further tested by measuring the shapes of two simple β-spectra ( 143Pr and 185W) and two inner group β-spectra ( 198Au and 86Rb) in coincidence with the subsequently emitted γ-rays. The γ-ray pulse, detected by a NaI well counter that envelops the beta spectrometer, supplied the gate to the 400-channel pulse-height analyser. In all cases, the results of these measurements are in good agreement with those previously reported. The beta spectrum of the 170Tm decay to the first excited level in 170Yb was measured in coincidence with the 84 keV gamma ray. The experiment was performed under the same measurement conditions used for the 198Au and 86Rb experiments. The spectrum exhibits a definite non-statistical energy dependence, falling below any straight line Fermi-Kurie plot fit at low energies. The shape factor was fitted by a polynomial of the form 1+ aW+ b/ W+ cW 2. A good fit was obtained for a = 1.11, b = −0.85, c = − 0.24. The end-point of this transition was determined to be 879±7 keV.

Beta-spectrum shape factor of P 32

We have measured the β spectrum shape of P 32 with an intermediate image β ray spectrometer and compared our results with those of other experiments. The average of the various results on the spectrum shape factoryyields a slope of 9% ( mc 2 −1 from 300 keV to 600 keV and about 1% from 600 keV to 1650 keV.

O+↔O− БЕтА-пЕРЕхОДы

In the paper, the reasons of similarity between first forbidden beta-transitions and the allowed ones, are investigated. The shape of beta-spectra, the degree of longitudinal polarization and 1g ft — values are considered in the particular (O+↔O−) case. The results of analyses are used for comparison of the consequences of the “Conservent Vector Current” with experimental data. It is shown, that CVC is not in contradiction with them.

The shape of the allowed positron spectrum of Na22

The shape of the allowed positron spectrum from the decay of Na22 has been studied under various experimental conditions in an ironfree, double-focusing spectrometer in search of instrumental distortions of the spectrum. The possibility of positrons back-scattering from the material directly behind the source on the optical path of the positrons was studied. The beta spectrum shape was measured with end-plates (located ∼6.5 cm behind the source) of aluminum, lucite and lead. Different spectrometer baffle settings were also used. No differences were observed in the spectrum shapes taken under the different experimental conditions. The experimental shape factor could be fitted with an empirical shape of the form of (1+b/W) with 0.10≲b≲0.3 in agreement with earlier work.

ELECTRON SPECTROSCOPY IN HEALTH PHYSICS RESEARCH.

Electron spectrometers may be classified by the energydifferentiating mcchanism employed, as magnetic, electrostatic, scintillation, proportional counter, or semiconductor. Each type offers particular combinations of transmission, resolution, and energy acceptance from 0.01 to 100 per cent, 0.001 to 25 per ccnt, and 1 ev to many Mev, respectively. Solid sources are usually used and these sources may range in diameter from a fraction of a mm to 10 cm. Energy calibration is usually accomplished using internal conversion electrons or an electron gun or accelerator. Measurement of transmission is made by noting deviation, if any, from a Fermi plot of an experimental BETA spectrum from an allowed transition. Uses in health physics include measurements of: shapes of BETA spectra which determinie shapes of BETA -absorption curves, branching ratios, and average energies per disintegration, all of which are used in internal dose calculations; cross sections for electron-electron interactions in solids and gases; slowing down spectra of BETA rays, Compton- and photoelectrons in solids; BETA -spectra from unknown emitters for identification. As monochromators, they select a narrow energy band from a BETA -ray continuum which may be used to measure efficiency of scintillators and energy dependence of BETA -ray dosimeters. (auth)

Second forbidden Coulomb beta transitions

Second forbidden Coulomb beta-transitions are investigated and it is shown that the shape of the second forbidden Coulomb beta spectrum is similar to that of unique first forbidden transitions and that e.g. transitions in Tc 99, I 129 and Cs 135 may be interpreted as Coulomb transitions. Experiments are discussed which could verify this assumption.

Shape of Beta Spectra of Once Forbidden Transitions in the Decays ofGa72,La140,Eu152,Eu154, andSb124

Magnetic spectrometer studies were made on the beta spectra of Ga/sup 72/ , La/sup 140/, E/sup 152/, Eu/sup 154/, and Sb/sup 124/. Th e highest energy beta group of each of these transitions has an abnormally long comparative half life and probably is a once forbidden decay from a 3-- initial state to a 2+ final state. The highest energy beta spectrum was found to have a nonstatistical, nonunique shape. On the assumption that the B/sub ij/ matrix element dominates the decay, the experimental shape factors were fitted empirically by C = q/sup 2/ + to 15, 10, 5, 20, and 15 for Ga/sup 72/, La/sup 140/ , Eu/sup 152/, Eu/sup 154/, and Sb/sup 124/, respectively. (auth)

Approximate formulas describing transmission and absorption of beta rays.

Ignoring the complicated mechanisms governing the absorption of beta rays (reduction of the energy of single beta particles, complete arrest of low-energetic beta particles, elastic and inelastic scattering, shape of beta spectrum etc.) it is sometimes useful to describe the study of the phenomena in over-all transmission or absorption in simple mathematical formulas. Either the reduction of the number of particles or the energy loss of the beam of beta rays may be considered in trans

Effect of Atomic Electron Screening on the Shape of Forbidden Beta Spectra

In Fermi's theory of beta decay the influence of the atomic electrons on the shape of the spectra is often disregarded since the influence is small except at low energies. However, there is some interest in knowing exactly how small it is. This paper gives an approximate calculation of the screening effect, both for allowed and for forbidden spectra. The Thomas-Fermi model for the atomic electrons and WKB approximations for the wave functions of the emitted particles are used. The results for the allowed spectra agree with those of Rose and of Longmire and Brown. The calculations for the forbidden spectra lead to a simple rule for finding the screening effect in any specific case.

Window Correction Curves and the Shape of Beta-Spectra

Window Correction Curves and the Shape of Beta-Spectra