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)

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

WeisskopfSingleParticleModel()

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

strength_function()

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.

transmission_coefficient()

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.

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

• /Users/gardiner/marley/include/marley/WeisskopfSingleParticleModel.hh
• /Users/gardiner/marley/src/WeisskopfSingleParticleModel.cc