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MuonCalib::BFieldCorFunc Class Reference

#include <BFieldCorFunc.h>

Inheritance diagram for MuonCalib::BFieldCorFunc:
Collaboration diagram for MuonCalib::BFieldCorFunc:

Public Types

using ParVec = std::vector< double >
 

Public Member Functions

 BFieldCorFunc (const std::string &quality, const CalibFunc::ParVec &parameters, const IRtRelation *rt)
 Constructor: quality = "high", slow but accurate initialization initialization of the correction function, quality = "medium", compromise between speed and accuracy of the initialization of the correction function (default), quality = "low", fast initialization of the correction function at the price of lower quality. More...
 
 BFieldCorFunc (const CalibFunc::ParVec &parameters, const IRtRelation *rt)
 Constructor: parameters[0] = high voltage [V], parameters[1] = \( \epsilon \),. More...
 
double epsilon () const
 < get the \( \epsilon \) parameter of the B-field correction function More...
 
void setRtRelationship (const IRtRelation &rt)
 < set the \( \epsilon \) parameter of the B-field correction function = eps More...
 
std::string name () const
 get the class name More...
 
double correction (double t, double B_wire, double B_mu) const
 get t(r, \( \vec{B} \)!=0)-t(r, \( \vec{B} \)=0); t = drift time t [ns] for B=0; B_wire = magnetic field parallel to the anode wire of the given tube, B_mu = magnetic field orthogonal to the wire and parallel to the muon trajectory in the given tube [B] = Tesla More...
 
double correction_to_B (double t, double B_wire, double B_mu, double B_factor=-1.0) const
 
virtual std::string typeName () const
 
unsigned int nPar () const
 
const ParVec & parameters () const
 
double par (unsigned int index) const
 

Private Member Functions

void init (const std::string &quality, const CalibFunc::ParVec &params, const IRtRelation *rt)
 
double t_from_r (const double r, const IRtRelation *rt) const
 
double integral (const double r_min, const double r_max, const IRtRelation *rt) const
 

Private Attributes

std::vector< double > m_param {}
 
std::string m_quality {}
 
double m_step_size {0.}
 
Amg::VectorX m_alpha
 
double m_t_min {-std::numeric_limits<double>::max()}
 
double m_t_max {std::numeric_limits<double>::max()}
 
double m_r_min {-std::numeric_limits<double>::max()}
 
double m_r_max {std::numeric_limits<double>::max()}
 
ParVec m_parameters {}
 

Detailed Description

This class allows the user to get the difference between the drift time measured by a tube operated in a magnetic field \( \vec{B} \) and the drift time which would be measured by this tube if \( \vec{B} \) vanished.

Correction:

\[ t(r,\vec{B}) = t(r,\vec{B}=0) + B_\perp^{2-\epsilon}\cdot \int\limits_{25\ \mu m}^{r} \frac{v_{B=0}^{1-\epsilon}(r')} {E^{2-\epsilon}(r')}\,dr' \]

.

\( B_\perp = |\vec{B}_\perp| \); \( \vec{B}_\perp = \vec{B}_{wire}+\vec{B}_\mu \);

\( \vec{B}_{wire} \): magnetic field parallel to the anode wire of the given tube;

\( \vec{B}_\mu \): magnetic field magnetic field perpendicular to wire and parallel to the muon trajectory in the given tube.

Definition at line 47 of file BFieldCorFunc.h.

Member Typedef Documentation

◆ ParVec

using MuonCalib::CalibFunc::ParVec = std::vector<double>
inherited

Definition at line 35 of file CalibFunc.h.

Constructor & Destructor Documentation

◆ BFieldCorFunc() [1/2]

BFieldCorFunc::BFieldCorFunc ( const std::string &  quality,
const CalibFunc::ParVec &  parameters,
const IRtRelation *  rt 
)
explicit

Constructor: quality = "high", slow but accurate initialization initialization of the correction function, quality = "medium", compromise between speed and accuracy of the initialization of the correction function (default), quality = "low", fast initialization of the correction function at the price of lower quality.

parameters[0] = high voltage [V], parameters[1] = \( \epsilon \),

Definition at line 20 of file BFieldCorFunc.cxx.

20  :
21  IMdtBFieldCorFunc(parameters) {
22  init(quality, parameters, rt);
23 }

◆ BFieldCorFunc() [2/2]

BFieldCorFunc::BFieldCorFunc ( const CalibFunc::ParVec &  parameters,
const IRtRelation *  rt 
)
explicit

Constructor: parameters[0] = high voltage [V], parameters[1] = \( \epsilon \),.

Definition at line 25 of file BFieldCorFunc.cxx.

25  :
26  IMdtBFieldCorFunc(parameters) {
27  init("medium", parameters, rt);
28 }

Member Function Documentation

◆ correction()

double BFieldCorFunc::correction ( double  t,
double  B_wire,
double  B_mu 
) const
virtual

get t(r, \( \vec{B} \)!=0)-t(r, \( \vec{B} \)=0); t = drift time t [ns] for B=0; B_wire = magnetic field parallel to the anode wire of the given tube, B_mu = magnetic field orthogonal to the wire and parallel to the muon trajectory in the given tube [B] = Tesla

Implements MuonCalib::IMdtBFieldCorFunc.

Definition at line 182 of file BFieldCorFunc.cxx.

182  {
184  // VARIABLES //
186  double B_perp{std::hypot(B_wire, B_mu)}; // B orthogonal to the
187  // electron drift path
188  double B_factor{std::pow(B_perp, 2.0 - m_param[1])};
189  double precision{0.1}; // precision of the correction in ns
190  double t_max{t}; // upper time search limit
191  double t_min{t - 2 * correction_to_B(t, B_wire, B_mu, B_factor)}; // lower time search limit
192  if (t_min < m_t_min) t_min = m_t_min;
193  double time{t}; // auxiliary time variable
194  double integ{0.0}; // integral
195  double tmean{0.5 * (m_t_min + m_t_max)}; // mean time
196  double tlength{m_t_max - m_t_min}; // length of drift-time interval
197 
199  // DRIFT TIME CHECK //
201  if (t <= m_t_min) { return 0.0; }
202  if (t > m_t_max) {
203  t_max = m_t_max;
204  time = m_t_max;
205  }
206 
208  // SEARCH FOR THE CORRECTED DRIFT TIME //
210  while (t_max - t_min > precision) {
211  integ = 0.0;
212  for (int k = 0; k < m_alpha.rows(); k++) {
213  integ += m_alpha[k] * std::legendre(k, 2 * (0.5 * (t_min + t_max) - tmean) / tlength);
214  }
215  if (0.5 * (t_min + t_max) + B_factor * integ > time) {
216  t_max = 0.5 * (t_min + t_max);
217  } else {
218  t_min = 0.5 * (t_min + t_max);
219  }
220  }
221 
222  return B_factor * integ;
223 } // end BFieldCorFunc::correction

◆ correction_to_B()

double BFieldCorFunc::correction_to_B ( double  t,
double  B_wire,
double  B_mu,
double  B_factor = -1.0 
) const

Definition at line 225 of file BFieldCorFunc.cxx.

225  {
227  // VARIABLES //
229  if (B_factor < 0) {
230  const double B_perp{std::hypot(B_wire, B_mu)};
231  // B orthogonal to the electron drift path
232  B_factor = std::pow(B_perp, 2.0 - m_param[1]);
233  }
234  double time{t};
235  double integ{0.0}; // integral
236  double tmean{0.5 * (m_t_min + m_t_max)}; // mean time
237  double tlength{m_t_max - m_t_min}; // length of drift-time interval
238 
240  // DRIFT TIME CHECK //
242  if (t <= m_t_min) { return 0.0; }
243  if (t > m_t_max) { time = m_t_max; }
244 
246  // CALCULATE THE CORRECTION //
248  for (int k = 0; k < m_alpha.rows(); k++) {
249  integ += m_alpha[k] * std::legendre(k, 2 * (time - tmean) / tlength);
250  }
251 
252  return B_factor * integ;
253 } // end BFieldCorFunc::correction_to_B

◆ epsilon()

double BFieldCorFunc::epsilon ( ) const

< get the \( \epsilon \) parameter of the B-field correction function

Definition at line 175 of file BFieldCorFunc.cxx.

175 { return m_param[1]; }

◆ init()

void BFieldCorFunc::init ( const std::string &  quality,
const CalibFunc::ParVec &  params,
const IRtRelation *  rt 
)
private

Definition at line 30 of file BFieldCorFunc.cxx.

30  {
32  // PARAMETERS //
34  m_quality = quality;
35  m_param = params;
36 
38  // CONSISTENCY CHECK //
40  if (m_param.size() != 2) {
41  THROW_EXCEPTION("Wrong number of parameters!");
42  return;
43  }
44 
46  // VARIABLES //
48  unsigned int nb_points(31); // number of sample points for the integral
49  // in the correction function
50  double step{0.}; // r step size
51  double time{0.}; // auxiliary time variable
52  BaseFunctionFitter fitter(6); // 6 fit parameters for the integral by
53  // default ("medium quality")
54  LegendrePolynomial legendre{};
55 
57  // QUALITY SETTING //
59  if (m_quality == "high") {
60  fitter.set_number_of_coefficients(8);
61  nb_points = 31;
62  m_step_size = 0.02;
63  }
64  if (m_quality == "medium") {
65  fitter.set_number_of_coefficients(8);
66  nb_points = 31;
67  m_step_size = 0.06;
68  }
69  if (m_quality == "low") {
70  fitter.set_number_of_coefficients(8);
71  nb_points = 31;
72  m_step_size = 0.12;
73  }
74  // sample points for the integral factor in the correction function
75  std::vector<SamplePoint> sample_points(nb_points);
76 
78  // CALCULATE THE INTEGRAL PART OF THE CORRECTION FUNCTION //
80  m_t_min = (rt)->tLower();
81  m_t_max = (rt)->tUpper();
82 
83  // minimum and maximum radius //
84  m_r_min = 0.025 * CLHEP::mm; // minimum radius
85  m_r_max = rt->radius(m_t_max); // maximum radius
86  if (m_r_max > 17.0 || m_r_max < m_r_min) {
87  MsgStream log(Athena::getMessageSvc(), "BFieldCorFunc");
88  log << MSG::INFO << "UNPHYSICAL MAXIMUM DRIFT RADIUS OF " << m_r_max << ", WILL BE SET TO 17.0!" << endmsg;
89  m_r_max = 17.0;
90  }
91  step = ((m_r_max - m_r_min) / static_cast<double>(nb_points - 1));
92 
93  // set the sample points //
94  double prev_r = 0;
95  double prev_integral = 0;
96  for (unsigned int k = 0; k < nb_points; k++) {
97  time = t_from_r(m_r_min + k * step, rt);
98  sample_points[k].set_x1(2 * (time - 0.5 * (m_t_min + m_t_max)) / (m_t_max - m_t_min));
99  double new_r = rt->radius(time);
100  double new_integral = 1.0e9 * integral(prev_r, new_r, rt) + prev_integral;
101  sample_points[k].set_x2(new_integral);
102  sample_points[k].set_error(1.0);
103  prev_r = new_r;
104  prev_integral = new_integral;
105  }
106 
107  // perform the fit //
108  fitter.fit_parameters(sample_points, 1, nb_points, legendre);
109  m_alpha = fitter.coefficients();
110 
111 } // end BFieldCorFunc::init

◆ integral()

double BFieldCorFunc::integral ( const double  r_min,
const double  r_max,
const IRtRelation *  rt 
) const
private

Definition at line 140 of file BFieldCorFunc.cxx.

140  {
141  // catch fp exceptions//
142  if (m_r_min < 1e-10 || r_min < m_r_min) return 0.0;
143 
145  // VARIABLES //
147  const double E0{m_param[0] / std::log(m_r_max / m_r_min)}; // E(r)=E0/r
148  double radius{r_max};
149  double rp{r_min}; // auxiliary radius variables
150  double integ{0.0}; // current value of the integral
151  // double step(0.010); // integration step size [mm]
152  double step{m_step_size}; // integration step size [mm]
153  double time{0.}; // drift time
154 
156  // r IN [m_r_min, m_r_max]? //
158  if (r_max < r_min) { return 0.0; }
159  if (r_max > m_r_max) { radius = m_r_max; }
160 
162  // INTEGRATION //
164  double delta = step;
165  while (rp < radius) {
166  time = t_from_r(rp, rt);
167  if (rp + step > radius) delta = radius - rp;
168  integ += 1.0e-3 * delta * std::pow(std::abs(rt->driftVelocity(time)) * 1.0e6, 1.0 - m_param[1]) /
169  std::pow(E0 / (rp * 1.0e-3), 2.0 - m_param[1]);
170  rp += step;
171  }
172 
173  return integ;
174 } // end BFieldCorFunc::integral

◆ name()

std::string BFieldCorFunc::name ( ) const
virtual

get the class name

get t(r, \( \vec{B} \) !=0)-t(r, \( \vec{B} \) =0); t = measured drift time t [ns]; B_wire = magnetic field parallel to the anode wire of the given tube, B_mu = magnetic field orthogonal to the wire and parallel to the muon trajectory in the given tube [B] = Tesla

Implements MuonCalib::CalibFunc.

Definition at line 180 of file BFieldCorFunc.cxx.

180 { return std::string("BFieldCorFunc"); }

◆ nPar()

unsigned int MuonCalib::CalibFunc::nPar ( ) const
inlineinherited

Definition at line 39 of file CalibFunc.h.

39 { return m_parameters.size(); }

◆ par()

double MuonCalib::CalibFunc::par ( unsigned int  index) const
inlineinherited

Definition at line 41 of file CalibFunc.h.

41  {
42  return index < nPar() ? m_parameters[index] : 0.;
43  }

◆ parameters()

const ParVec& MuonCalib::CalibFunc::parameters ( ) const
inlineinherited

Definition at line 40 of file CalibFunc.h.

40 { return m_parameters; }

◆ setRtRelationship()

void BFieldCorFunc::setRtRelationship ( const IRtRelation &  rt)

< set the \( \epsilon \) parameter of the B-field correction function = eps

< set the r-t relationship used to calculate the B field correction to the measured drift time = rt

Definition at line 176 of file BFieldCorFunc.cxx.

176  {
177  init(m_quality, m_param, &rt);
178 }

◆ t_from_r()

double BFieldCorFunc::t_from_r ( const double  r,
const IRtRelation *  rt 
) const
private

Definition at line 112 of file BFieldCorFunc.cxx.

112  {
114  // VARIABLES //
116  constexpr double precision{0.010}; // spatial precision of the inversion
117  double t_max{m_t_max}; // upper time search limit
118  double t_min{m_t_min}; // lower time search limit
119  double r_max{m_r_max}; // upper radius search limit
120  double r_min{m_r_min}; // lower radius search limit
122  // SEARCH FOR THE CORRESPONDING DRIFT TIME //
124  double t_guess, r_guess;
125 
126  do {
127  t_guess = t_min + (t_max - t_min) / (r_max - r_min) * (r - r_min);
128  r_guess = rt->radius(t_guess);
129  if (r_guess > r) {
130  r_max = r_guess;
131  t_max = t_guess;
132  } else {
133  r_min = r_guess;
134  t_min = t_guess;
135  }
136  } while (t_max - t_min > 0.1 && std::abs(r_guess - r) > precision);
137  return t_guess;
138 } // end BFieldCorFunc::t_from_r

◆ typeName()

virtual std::string MuonCalib::IMdtBFieldCorFunc::typeName ( ) const
inlinevirtualinherited

Implements MuonCalib::CalibFunc.

Definition at line 18 of file IMdtBFieldCorFunc.h.

18 { return "IMdtBFieldCorFunc"; }

Member Data Documentation

◆ m_alpha

Amg::VectorX MuonCalib::BFieldCorFunc::m_alpha
private

Definition at line 109 of file BFieldCorFunc.h.

◆ m_param

std::vector<double> MuonCalib::BFieldCorFunc::m_param {}
private

Definition at line 102 of file BFieldCorFunc.h.

◆ m_parameters

ParVec MuonCalib::CalibFunc::m_parameters {}
privateinherited

Definition at line 48 of file CalibFunc.h.

◆ m_quality

std::string MuonCalib::BFieldCorFunc::m_quality {}
private

Definition at line 105 of file BFieldCorFunc.h.

◆ m_r_max

double MuonCalib::BFieldCorFunc::m_r_max {std::numeric_limits<double>::max()}
private

Definition at line 120 of file BFieldCorFunc.h.

◆ m_r_min

double MuonCalib::BFieldCorFunc::m_r_min {-std::numeric_limits<double>::max()}
private

Definition at line 119 of file BFieldCorFunc.h.

◆ m_step_size

double MuonCalib::BFieldCorFunc::m_step_size {0.}
private

Definition at line 106 of file BFieldCorFunc.h.

◆ m_t_max

double MuonCalib::BFieldCorFunc::m_t_max {std::numeric_limits<double>::max()}
private

Definition at line 117 of file BFieldCorFunc.h.

◆ m_t_min

double MuonCalib::BFieldCorFunc::m_t_min {-std::numeric_limits<double>::max()}
private

Definition at line 116 of file BFieldCorFunc.h.

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