MARLEY (Model of Argon Reaction Low Energy Yields)  v1.1.0 A Monte Carlo event generator for tens-of-MeV neutrino-nucleus interactions in liquid argon
marley::WeisskopfSingleParticleModel Class Reference

Implements the Weisskopf single-particle estimates of the gamma-ray strength functions. More...

#include <WeisskopfSingleParticleModel.hh>

Inheritance diagram for marley::WeisskopfSingleParticleModel:

## Public Member Functions

WeisskopfSingleParticleModel (int Z, int A, double D0=1.)

virtual double strength_function (TransitionType type, int l, double e_gamma) override
Returns the gamma-ray strength function (MeV –2 $$\ell$$–1) for the requested gamma energy and multipolarity. More...

virtual double transmission_coefficient (TransitionType type, int l, double e_gamma) override
Returns the gamma-ray transmission coefficient (dimensionless) for the requested gamma energy and multipolarity. More...

Public Member Functions inherited from marley::GammaStrengthFunctionModel
GammaStrengthFunctionModel (int Z, int A)

double transmission_coefficient (double Exi, int twoJ, marley::Parity Pi, marley::Level &level_f)
Returns the gamma-ray transmission coefficient (dimensionless) for a transition from a given initial state to a final discrete Level. More...

Public Types inherited from marley::GammaStrengthFunctionModel
enum  TransitionType { electric, magnetic, unphysical }
Electromagnetic transitions in nuclei may be classified by their multipolarity (electric vs. magnetic multipole radiation)

Static Public Member Functions inherited from marley::GammaStrengthFunctionModel
static TransitionType determine_transition_type (int twoJi, marley::Parity Pi, int twoJf, marley::Parity Pf, int &l)
Determines whether a given electromagnetic transition between two nuclear states corresponds to electric or magnetic multipole radiation. More...

static TransitionType determine_transition_type (int twoJi, marley::Parity Pi, marley::Level &level_f, int &l)
Determines whether a given electromagnetic transition between two nuclear states corresponds to electric or magnetic multipole radiation. More...

static TransitionType determine_transition_type (marley::Level &level_i, marley::Level &level_f, int &l)
Determines whether a given electromagnetic transition between two nuclear states corresponds to electric or magnetic multipole radiation. More...

Static Protected Member Functions inherited from marley::GammaStrengthFunctionModel
static void check_multipolarity (int l)
Check that l > 0 and throw a marley::Error if it is not. More...

Protected Attributes inherited from marley::GammaStrengthFunctionModel
int A_
Mass number.

int Z_
Atomic number.

## Detailed Description

Implements the Weisskopf single-particle estimates of the gamma-ray strength functions.

Under this model, the electric ( $$f_{\text{E}\ell}$$) and magnetic ( $$f_{\text{M}\ell}$$) gamma-ray strength functions are independent of the gamma energy and are given by

$f_{\text{E}\ell} = \frac{2\alpha\Lambda}{\text{D}_0} \left(\frac{R}{\hbar c}\right)^{\!2\ell}$

and

$f_{\text{M}\ell} = 10\left(\frac{\hbar c} {R\,m_\text{p}}\right)^{\!2} f_{\text{E}\ell},$

where $$\alpha$$ is the fine-structure constant, $$\text{D}_0$$ is the level spacing parameter (MeV), $$R = (1.2\text{ fm})A^{1/3}$$ is the approximate nuclear radius, $$m_\text{p}$$ is the proton mass (MeV), and $$\Lambda$$ is a function of the multipolarity $$\ell$$ given by

$\Lambda \equiv \left(\frac{3}{\ell + 3}\right)^{\!2} \left(\frac{\ell + 1}{\ell\left[(2\ell + 1)!!\right]^2} \right).$

These estimates are typically only good to an order of magnitude, so using a more sophisticated model, e.g., the StandardLorentzianModel, is strongly recommended.

## Constructor & Destructor Documentation

 marley::WeisskopfSingleParticleModel::WeisskopfSingleParticleModel ( int Z, int A, double D0 = 1. )
Parameters
 Z Atomic number of the desired nuclide A Mass number of the desired nuclide D0 Level spacing parameter (MeV)

## Member Function Documentation

 double marley::WeisskopfSingleParticleModel::strength_function ( TransitionType type, int l, double e_gamma )
overridevirtual

Returns the gamma-ray strength function (MeV –2 $$\ell$$–1) for the requested gamma energy and multipolarity.

Parameters
 type Electric or magnetic transition l Multipolarity of the transition e_gamma Gamma-ray energy (MeV)
Note
As described above, the Weisskopf estimates of the gamma-ray strength functions are independent of the gamma energy, and so the parameter e_gamma is ignored by this function.

Implements marley::GammaStrengthFunctionModel.

 double marley::WeisskopfSingleParticleModel::transmission_coefficient ( TransitionType type, int l, double e_gamma )
overridevirtual

Returns the gamma-ray transmission coefficient (dimensionless) for the requested gamma energy and multipolarity.

The gamma-ray transmission coefficient and strength function are related via $$\text{T}_{\text{X}\ell}(\text{E}_\gamma) = 2\pi f_{\text{X}\ell}(\text{E}_\gamma)\text{E}_\gamma^{(2\ell + 1)},$$ where X is the type of transition (electric or magnetic), $$\ell$$ is the multipolarity, $$\text{T}_{\text{X}\ell}$$ is the transmission coefficient, $$f_{\text{X}\ell}$$ is the strength function, and $$\text{E}_\gamma$$ is the gamma-ray energy.

Parameters
 type Electric or magnetic transition l Multipolarity of the transition e_gamma Gamma-ray energy (MeV)

Implements marley::GammaStrengthFunctionModel.

The documentation for this class was generated from the following files: