Dead time correction calculator for muon detector data. More...

#include <PNeXus.h>

Inheritance diagram for nxH5::PNeXusDeadTime:

Collaboration diagram for nxH5::PNeXusDeadTime:

Public Member Functions
	PNeXusDeadTime (const PNeXus *nxs, bool debug=false)
	Constructor - initializes dead time calculator from NeXus data.

bool	IsValid ()
	Check if the dead time calculator was initialized successfully.

double	Up () const
	Get the error definition for the minimizer (FCNBase requirement)

double	operator() (const std::vector< double > &par) const
	Function call operator - calculates chi-square for given parameters.

void	Minimize (const int i)
	Minimize dead time for a specific detector spectrum.

const std::vector< hsize_t > &	GetDimensions () const
	Get the dimensions of the count dataset.

std::vector< float >	GetDeadTimeEstimated ()
	Get the estimated dead time values from minimization.

Private Attributes
bool	fDebug {false}
	Debug flag - if true, print additional diagnostic information.

bool	fValid
	Validity flag - true if required data was loaded successfully.

int	fGoodFrames {-1}
	Number of good time frames for analysis.

float	fTimeResolution {0.0}
	Time resolution in picoseconds.

std::vector< hsize_t >	fDims = {0, 0, 0}
	Dimensions of count data [periods, spectra, bins].

int	fT0Bin {-1}
	T0 bin number (time zero reference)

int	fFgbBin {-1}
	First good bin for analysis.

int	fLgbBin {-1}
	Last good bin for analysis.

std::vector< float >	fDeadTime
	Dead time values per detector (microseconds) from the file.

std::vector< float >	fDeadTimeEstimated
	Dead time values per detector (microseconds) as estimated from the data.

std::vector< int >	fCounts
	Count data for minimization.

double	fUp {0.5}
	UP parameter for Minuit2 (0.5 for chi-square)

unsigned int	fIdx {0}
	Current spectrum index being minimized.

Detailed Description

Dead time correction calculator for muon detector data.

The PNeXusDeadTime class calculates dead time corrections for muon detector count data using ROOT Minuit2 minimization. It inherits from ROOT::Minuit2::FCNBase to implement a chi-square minimization function.

Dead time is the period after detecting an event during which the detector cannot register another event. This class estimates the dead time parameter for each detector spectrum by minimizing the deviation from expected count rates.

Typical Usage:

nxH5::PNeXus nexus("file.nxs");
nxH5::PNeXusDeadTime ndt(&nexus, false);  // false = no debug output
 
if (ndt.IsValid()) {
    auto dims = ndt.GetDimensions();
    // Minimize for each spectrum
    for (unsigned int i = 0; i < dims[1]; i++) {
        ndt.minimize(i);
    }
}

Note: Requires a valid PNeXus object with count data; Uses ROOT Minuit2 for minimization

See also: ROOT::Minuit2::FCNBase; nxH5::PNeXus

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 1198 of file PNeXus.h.

Constructor & Destructor Documentation

◆ PNeXusDeadTime()

nxH5::PNeXusDeadTime::PNeXusDeadTime	(	const PNeXus *	nxs,
		bool	debug = false )

Constructor - initializes dead time calculator from NeXus data.

Reads count data, time resolution, and bin information from the NeXus file to set up the dead time calculation.
Parameters

nxs Pointer to PNeXus object containing the detector data

debug If true, print additional debug information during calculations
Note
After construction, check IsValid() to ensure data was loaded successfully

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.cpp, and /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 2793 of file PNeXus.cpp.

References fCounts, fDeadTime, fDeadTimeEstimated, fDebug, fDims, fFgbBin, fGoodFrames, fLgbBin, fT0Bin, fTimeResolution, and fValid.

Member Function Documentation

◆ GetDeadTimeEstimated()

std::vector< float > nxH5::PNeXusDeadTime::GetDeadTimeEstimated ( )

inline

Get the estimated dead time values from minimization.

Returns the dead time values calculated by the minimize() function for each spectrum. These values represent the dead time parameter that best fits the observed count data when accounting for dead time losses.

Returns: Vector of estimated dead time values (in microseconds) per spectrum

Note: Call minimize() for each spectrum before calling this method to populate the estimated values

See also: minimize() for the calculation method

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 1268 of file PNeXus.h.

References fDeadTimeEstimated.

◆ GetDimensions()

const std::vector< hsize_t > & nxH5::PNeXusDeadTime::GetDimensions ( ) const

inline

Get the dimensions of the count dataset.

Returns the dimensions [periods, spectra, bins] of the count data being used for dead time calculation.
Returns
Vector of dimension sizes (typically 3D: [periods, spectra, bins])

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 1251 of file PNeXus.h.

References fDims.

◆ IsValid()

bool nxH5::PNeXusDeadTime::IsValid ( )

inline

Check if the dead time calculator was initialized successfully.

Returns
true if required datasets were found and loaded, false otherwise

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 1215 of file PNeXus.h.

References fValid.

◆ Minimize()

void nxH5::PNeXusDeadTime::Minimize ( const int i )

Minimize dead time for a specific detector spectrum.

Performs Minuit2 minimization to find the optimal dead time parameter for the specified spectrum index. Results are printed to stdout.
Parameters

i Spectrum index to minimize (0-based index into second dimension)
Note
Prints minimization results including dead time estimate and errors

The index i must be less than dims[1] (number of spectra)
Performs ROOT Minuit2 minimization to find the optimal dead time parameter and count rate model parameters for the specified spectrum index. Uses MnMinimize with strategy 2 (high precision) and stores the result.

Minimization Parameters:

dtc: Dead time correction (initial: 0.01, step: 0.01)
N0: Initial count rate (initial: estimated from data)
N_bkg: Background rate (initial: 0.1)

Parameters

i	Spectrum index to minimize (0-based, must be < dims[1])

Note: Results are stored in fDeadTimeEstimated[i] and optionally printed to stdout if debug mode is enabled

See also: GetDeadTimeEstimated() to retrieve results after minimization

< Minuit2 function minimum result

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.cpp, and /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 2960 of file PNeXus.cpp.

References fCounts, fDeadTime, fDeadTimeEstimated, fDebug, fDims, fFgbBin, and fIdx.

◆ operator()()

double nxH5::PNeXusDeadTime::operator() ( const std::vector< double > & par ) const

Function call operator - calculates chi-square for given parameters.

Calculate the negative log-likelihood for dead time correction.

This is the objective function that ROOT::Minuit2 minimizes. It calculates the chi-square deviation between observed counts and expected counts corrected for dead time.
Parameters

par Vector of parameters (dead time values in microseconds)

Returns
Chi-square value for the given parameters
This function implements the objective function for ROOT Minuit2 minimization. It calculates the negative log-likelihood comparing observed counts to the expected count rate model with dead time correction.

Model: The expected count rate includes:

Exponential muon decay: N(t) = N0 * exp(-t/tau_mu) + N_bkg
Dead time correction: N_corrected = N(t) / (1 + N(t) * dtc)

Parameters:

par[0] (dtc): Dead time correction parameter
par[1] (N0): Initial count rate amplitude
par[2] (N_bkg): Background count rate

Parameters

par	Vector of parameters [dtc, N0, N_bkg]

Returns: Negative log-likelihood value to be minimized

Note: Uses the muon lifetime tau_mu = 2.1969811 microseconds

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.cpp, and /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 2920 of file PNeXus.cpp.

References fCounts, fDims, fFgbBin, fGoodFrames, fIdx, fLgbBin, fT0Bin, and fTimeResolution.

◆ Up()

double nxH5::PNeXusDeadTime::Up ( ) const

inline

Get the error definition for the minimizer (FCNBase requirement)

Returns the UP parameter which defines how the minimizer estimates errors. For chi-square minimization, UP = 0.5 corresponds to 1-sigma errors.
Returns
Error definition parameter (0.5 for chi-square)

Examples: /workspace/LMU/musrfit/src/external/nexus/PNeXus.h.

Definition at line 1223 of file PNeXus.h.

References fUp.

Member Data Documentation

◆ fCounts

std::vector<int> nxH5::PNeXusDeadTime::fCounts

private

Count data for minimization.

Definition at line 1281 of file PNeXus.h.

Referenced by Minimize(), operator()(), and PNeXusDeadTime().

◆ fDeadTime

std::vector<float> nxH5::PNeXusDeadTime::fDeadTime

private

Dead time values per detector (microseconds) from the file.

Definition at line 1279 of file PNeXus.h.

Referenced by Minimize(), and PNeXusDeadTime().

◆ fDeadTimeEstimated

std::vector<float> nxH5::PNeXusDeadTime::fDeadTimeEstimated

private

Dead time values per detector (microseconds) as estimated from the data.

Definition at line 1280 of file PNeXus.h.

Referenced by GetDeadTimeEstimated(), Minimize(), and PNeXusDeadTime().

◆ fDebug

bool nxH5::PNeXusDeadTime::fDebug {false}

private

Debug flag - if true, print additional diagnostic information.

Definition at line 1271 of file PNeXus.h.

Referenced by Minimize(), and PNeXusDeadTime().

◆ fDims

std::vector<hsize_t> nxH5::PNeXusDeadTime::fDims = {0, 0, 0}

private

Dimensions of count data [periods, spectra, bins].

Definition at line 1275 of file PNeXus.h.

Referenced by GetDimensions(), Minimize(), operator()(), and PNeXusDeadTime().

◆ fFgbBin

int nxH5::PNeXusDeadTime::fFgbBin {-1}

private

First good bin for analysis.

Definition at line 1277 of file PNeXus.h.

Referenced by Minimize(), operator()(), and PNeXusDeadTime().

◆ fGoodFrames

int nxH5::PNeXusDeadTime::fGoodFrames {-1}

private

Number of good time frames for analysis.

Definition at line 1273 of file PNeXus.h.

Referenced by operator()(), and PNeXusDeadTime().

◆ fIdx

unsigned int nxH5::PNeXusDeadTime::fIdx {0}

private

Current spectrum index being minimized.

Definition at line 1283 of file PNeXus.h.

Referenced by Minimize(), and operator()().

◆ fLgbBin

int nxH5::PNeXusDeadTime::fLgbBin {-1}

private

Last good bin for analysis.

Definition at line 1278 of file PNeXus.h.

Referenced by operator()(), and PNeXusDeadTime().

◆ fT0Bin

int nxH5::PNeXusDeadTime::fT0Bin {-1}

private

T0 bin number (time zero reference)

Definition at line 1276 of file PNeXus.h.

Referenced by operator()(), and PNeXusDeadTime().

◆ fTimeResolution

float nxH5::PNeXusDeadTime::fTimeResolution {0.0}

private

Time resolution in picoseconds.

Definition at line 1274 of file PNeXus.h.

Referenced by operator()(), and PNeXusDeadTime().

◆ fUp

double nxH5::PNeXusDeadTime::fUp {0.5}

private

UP parameter for Minuit2 (0.5 for chi-square)

Definition at line 1282 of file PNeXus.h.

Referenced by Up().

◆ fValid

bool nxH5::PNeXusDeadTime::fValid

private

Validity flag - true if required data was loaded successfully.

Definition at line 1272 of file PNeXus.h.

Referenced by IsValid(), and PNeXusDeadTime().

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

/workspace/LMU/musrfit/src/external/nexus/PNeXus.h
/workspace/LMU/musrfit/src/external/nexus/PNeXus.cpp

nxs	Pointer to PNeXus object containing the detector data
debug	If true, print additional debug information during calculations

Public Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ PNeXusDeadTime()

Member Function Documentation

◆ GetDeadTimeEstimated()

◆ GetDimensions()

◆ IsValid()

◆ Minimize()

◆ operator()()

◆ Up()

Member Data Documentation

◆ fCounts

◆ fDeadTime

◆ fDeadTimeEstimated

◆ fDebug

◆ fDims

◆ fFgbBin

◆ fGoodFrames

◆ fIdx

◆ fLgbBin

◆ fT0Bin

◆ fTimeResolution

◆ fUp

◆ fValid