scholarly journals Precision branching-ratio measurements in $$^{18}$$O

2021 ◽  
Vol 57 (4) ◽  
Author(s):  
S. Pirrie ◽  
C. Wheldon ◽  
Tz. Kokalova ◽  
J. Bishop ◽  
Th. Faestermann ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Branching Ratio ◽  
High Energy ◽  
Branching Ratios ◽  
Monte Carlo Techniques ◽  
Energy States

AbstractAn experiment has been performed utilising the $$^{12}$$ 12 C($$^{7}$$ 7 Li,p)$$^{18}$$ 18 O reaction to populate high-energy states in $$^{18}$$ 18 O. Using the Munich Q3D magnetic spectrograph in conjunction with the Birmingham large-angular-coverage DSSD array, branching ratios have been measured for over fifty states in $$^{18}$$ 18 O, investigating the $$\alpha $$ α -decay, n-decay, 2n-decay and $$\gamma $$ γ -decay branches. In tandem, Monte-Carlo techniques have been used to identify and separate features.

scholarly journals Clustering in $^{18}$O - absolute determination of branching ratios via high-resolution particle spectroscopy

2020 ◽  
Author(s):  
Stuart Pirrie ◽  
Carl Wheldon ◽  
Tzany Kokalova ◽  
Jack Bishop ◽  
R. Hertenberger ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Excited State ◽  
High Resolution ◽  
Cluster Structure ◽  
High Energy ◽  
Branching Ratios ◽  
Light Nuclei ◽  
Decay Channels ◽  
Monte Carlo Techniques

The determination of absolute branching ratios for high-energy states in light nuclei is an important and useful tool for probing the underlying nuclear structure of individual resonances: for example, in establishing the tendency of an excited state towards \alphaα-cluster structure. Difficulty arises in measuring these branching ratios due to similarities in available decay channels, such as (\mathbf{^{18}}18O,\mathbf{n}𝐧) and (\mathbf{^{18}}18O,\mathbf{2n}2𝐧), as well as differences in geometric efficiencies due to population of bound excited levels in daughter nuclei. Methods are presented using Monte Carlo techniques to overcome these issues.

Neutron dose evaluation of Elekta Linac at two energies (10 & 18 MV) by MCNP code and comparison with experimental measurements

2014 ◽  
Vol 6 (1) ◽  
pp. 1006-1015
Author(s):  
Negin Shagholi ◽  
Hassan Ali ◽  
Mahdi Sadeghi ◽  
Arjang Shahvar ◽  
Hoda Darestani ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Measurement Data ◽  
Calculated Data ◽  
High Energy ◽  
Neutron Dose ◽  
Dose Assessment ◽  
Photon Flux ◽  
Dose Equivalent ◽  
Monte Carlo Techniques ◽  
Neutron Dose Equivalent

Medical linear accelerators, besides the clinically high energy electron and photon beams, produce other secondary particles such as neutrons which escalate the delivered dose. In this study the neutron dose at 10 and 18MV Elekta linac was obtained by using TLD600 and TLD700 as well as Monte Carlo simulation. For neutron dose assessment in 2020 cm2 field, TLDs were calibrated at first. Gamma calibration was performed with 10 and 18 MV linac and neutron calibration was done with 241Am-Be neutron source. For simulation, MCNPX code was used then calculated neutron dose equivalent was compared with measurement data. Neutron dose equivalent at 18 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 3.3, 4, 5 and 6 cm. Neutron dose at depths of less than 3.3cm was zero and maximized at the depth of 4 cm (44.39 mSvGy-1), whereas calculation resulted  in the maximum of 2.32 mSvGy-1 at the same depth. Neutron dose at 10 MV was measured by using TLDs on the phantom surface and depths of 1, 2, 2.5, 3.3, 4 and 5 cm. No photoneutron dose was observed at depths of less than 3.3cm and the maximum was at 4cm equal to 5.44mSvGy-1, however, the calculated data showed the maximum of 0.077mSvGy-1 at the same depth. The comparison between measured photo neutron dose and calculated data along the beam axis in different depths, shows that the measurement data were much more than the calculated data, so it seems that TLD600 and TLD700 pairs are not suitable dosimeters for neutron dosimetry in linac central axis due to high photon flux, whereas MCNPX Monte Carlo techniques still remain a valuable tool for photonuclear dose studies.

scholarly journals Measurement of the structure of potential cluster bands and absolute branching ratios of high-energy states in 18O*

2020 ◽  
Vol 1643 ◽  
pp. 012155
Author(s):  
S. Pirrie ◽  
C. Wheldon ◽  
Tz. Kokalova ◽  
J. Bishop ◽  
R. Hertenberger ◽  
...  
Keyword(s):  
High Energy ◽  
Branching Ratios ◽  
Energy States

scholarly journals Lepton-flavor-violating decays of the SM-like Higgs boson $h\rightarrow e_ie_j$, and $e_i \rightarrow e_j\, \gamma $ in a flipped 3-3-1 model

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
T T Hong ◽  
H T Hung ◽  
H H Phuong ◽  
L T T Phuong ◽  
L T Hue
Keyword(s):  
Higgs Boson ◽  
Branching Ratio ◽  
High Energy ◽  
Branching Ratios ◽  
The Other ◽  
Experimental Limit ◽  
Lepton Flavor ◽  
The Standard Model ◽  
Charged Leptons ◽  
O 10

Abstract In the framework of the flipped 3-3-1 model introduced recently [R. M. Fonseca and M. Hirsch, J. High Energy Phys. 1608, 003 (2016)], the lepton-flavor-violating (LFV) decay $\mu \rightarrow 3e$ was predicted to have a large branching ratio (Br) close to the recent experimental limit. We will show that the Br of LFV decays of the standard-model-like (SM-like) Higgs boson decays (LFVHD) Br$(h\rightarrow e_ae_b)$ may also be large. Namely, Br$(h\rightarrow \mu\tau,e\tau)$ can reach values of $\mathcal{O}(10^{-4}){-}\mathcal{O}(10^{-5})$, which will reach the upcoming experimental sensitivities. On the other hand, for LFV decays of charged leptons (cLFV) $(e_b\rightarrow e_a\gamma)$, the branching ratios are well below experimental bounds.

scholarly journals Angular Correlation Measurements in 33S

1977 ◽  
Vol 30 (1) ◽  
pp. 23 ◽  
Author(s):  
JR Southon ◽  
AR Poletti ◽  
DJ Beale
Keyword(s):  
Excitation Energy ◽  
Angular Correlation ◽  
High Energy ◽  
Branching Ratios ◽  
Angular Correlations ◽  
Mixing Ratios ◽  
Weak Decays ◽  
Energy States

The 32S(d, p) reaction has been used to excite states in 33S. Proton-gamma angular correlations for states up to 4�43 MeV in excitation energy have been measured to determine spins and y-ray branching and multipole mixing ratios. Results obtained for mixing ratios include 0(1� 97-+0) = 0'75�0'38, 0(2'93-+0) = 0�19�0�14 and 0(2'93-+1'97) = O�OO�O�04. Spin and parity assignments of 3/2 + and (1/2+, 3/2�) have been found for the 3� 94 and 4�43 MeV states respectively. Branching ratios have been determined for several previously unreported weak decays from high energy states.

High-energy electron and X-ray scattering from H2 using Monte Carlo techniques

1995 ◽  
Vol 56 (S29) ◽  
pp. 627-630 ◽  
Author(s):  
S. A. Alexander ◽  
R. L. Coldwell ◽  
Ruth E. Hoffmeyer ◽  
Ajit J. Thakkar
Keyword(s):  
Monte Carlo ◽  
High Energy ◽  
Energy Electron ◽  
High Energy Electron ◽  
X Ray ◽  
Monte Carlo Techniques ◽  
X Ray Scattering ◽  
Ray Scattering

Monte Carlo Modelling of Secondary Electron Yield from Rough Surfaces

1990 ◽  
Vol 48 (1) ◽  
pp. 422-423
Author(s):  
John C. Russ
Keyword(s):  
Monte Carlo ◽  
Energy Loss ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Analytical Calculation ◽  
Mean Free Path ◽  
Single Scattering ◽  
High Energy ◽  
Secondary Electron Yield ◽  
Electron Yield

Monte-Carlo programs are well recognized for their ability to model electron beam interactions with samples, and to incorporate boundary conditions such as compositional or surface variations which are difficult to handle analytically. This success has been especially powerful for modelling X-ray emission and the backscattering of high energy electrons. Secondary electron emission has proven to be somewhat more difficult, since the diffusion of the generated secondaries to the surface is strongly geometry dependent, and requires analytical calculations as well as material parameters. Modelling of secondary electron yield within a Monte-Carlo framework has been done using multiple scattering programs, but is not readily adapted to the moderately complex geometries associated with samples such as microelectronic devices, etc.This paper reports results using a different approach in which simplifying assumptions are made to permit direct and easy estimation of the secondary electron signal from samples of arbitrary complexity. The single-scattering program which performs the basic Monte-Carlo simulation (and is also used for backscattered electron and EBIC simulation) allows multiple regions to be defined within the sample, each with boundaries formed by a polygon of any number of sides. Each region may be given any elemental composition in atomic percent. In addition to the regions comprising the primary structure of the sample, a series of thin regions are defined along the surface(s) in which the total energy loss of the primary electrons is summed. This energy loss is assumed to be proportional to the generated secondary electron signal which would be emitted from the sample. The only adjustable variable is the thickness of the region, which plays the same role as the mean free path of the secondary electrons in an analytical calculation. This is treated as an empirical factor, similar in many respects to the λ and ε parameters in the Joy model.

Bayesian Estimation of DSGE Models

2015 ◽  
Author(s):  
Edward P. Herbst ◽  
Frank Schorfheide
Keyword(s):  
Monte Carlo ◽  
Sequential Monte Carlo ◽  
Likelihood Function ◽  
Academic Research ◽  
Dynamic Stochastic General Equilibrium ◽  
Computational Techniques ◽  
Dsge Models ◽  
Monte Carlo Techniques ◽  
Dynamic Stochastic ◽  
Theoretical Foundations

Dynamic stochastic general equilibrium (DSGE) models have become one of the workhorses of modern macroeconomics and are extensively used for academic research as well as forecasting and policy analysis at central banks. This book introduces readers to state-of-the-art computational techniques used in the Bayesian analysis of DSGE models. The book covers Markov chain Monte Carlo techniques for linearized DSGE models, novel sequential Monte Carlo methods that can be used for parameter inference, and the estimation of nonlinear DSGE models based on particle filter approximations of the likelihood function. The theoretical foundations of the algorithms are discussed in depth, and detailed empirical applications and numerical illustrations are provided. The book also gives invaluable advice on how to tailor these algorithms to specific applications and assess the accuracy and reliability of the computations. The book is essential reading for graduate students, academic researchers, and practitioners at policy institutions.

scholarly journals Disentangling QCD and new physics in D → πℓ+ℓ−

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Aoife Bharucha ◽  
Diogo Boito ◽  
Cédric Méaux
Keyword(s):  
Standard Model ◽  
Branching Ratio ◽  
Branching Ratios ◽  
New Physics ◽  
Operator Product ◽  
Beyond The Standard Model ◽  
Spectral Functions ◽  
The Standard Model ◽  
Model Independent ◽  
Weak Annihilation

Abstract In this paper we consider the decay D+ → π+ℓ+ℓ−, addressing in particular the resonance contributions as well as the relatively large contributions from the weak annihilation diagrams. For the weak annihilation diagrams we include known results from QCD factorisation at low q2 and at high q2, adapting the existing calculation for B decays in the Operator Product Expansion. The hadronic resonance contributions are obtained through a dispersion relation, modelling the spectral functions as towers of Regge-like resonances in each channel, as suggested by Shifman, imposing the partonic behaviour in the deep Euclidean. The parameters of the model are extracted using e+e− → (hadrons) and τ → (hadrons) + ντ data as well as the branching ratios for the resonant decays D+ → π+R(R → ℓ+ℓ−), with R = ρ, ω, and ϕ. We perform a thorough error analysis, and present our results for the Standard Model differential branching ratio as a function of q2. Focusing then on the observables FH and AFB, we consider the sensitivity of this channel to effects of physics beyond the Standard Model, both in a model independent way and for the case of leptoquarks.

scholarly journals Stochastic Order and Generalized Weighted Mean Invariance

Entropy ◽  
2021 ◽  
Vol 23 (6) ◽  
pp. 662
Author(s):  
Mateu Sbert ◽  
Jordi Poch ◽  
Shuning Chen ◽  
Víctor Elvira
Keyword(s):  
Monte Carlo ◽  
Probability Distributions ◽  
Stochastic Order ◽  
Arithmetic Mean ◽  
Stochastic Orders ◽  
Arithmetic Means ◽  
Increasing Convex Order ◽  
Monte Carlo Techniques ◽  
Multiple Importance Sampling ◽  
Invariance Properties

In this paper, we present order invariance theoretical results for weighted quasi-arithmetic means of a monotonic series of numbers. The quasi-arithmetic mean, or Kolmogorov–Nagumo mean, generalizes the classical mean and appears in many disciplines, from information theory to physics, from economics to traffic flow. Stochastic orders are defined on weights (or equivalently, discrete probability distributions). They were introduced to study risk in economics and decision theory, and recently have found utility in Monte Carlo techniques and in image processing. We show in this paper that, if two distributions of weights are ordered under first stochastic order, then for any monotonic series of numbers their weighted quasi-arithmetic means share the same order. This means for instance that arithmetic and harmonic mean for two different distributions of weights always have to be aligned if the weights are stochastically ordered, this is, either both means increase or both decrease. We explore the invariance properties when convex (concave) functions define both the quasi-arithmetic mean and the series of numbers, we show its relationship with increasing concave order and increasing convex order, and we observe the important role played by a new defined mirror property of stochastic orders. We also give some applications to entropy and cross-entropy and present an example of multiple importance sampling Monte Carlo technique that illustrates the usefulness and transversality of our approach. Invariance theorems are useful when a system is represented by a set of quasi-arithmetic means and we want to change the distribution of weights so that all means evolve in the same direction.

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