#include <G4UCNMaterialPropertiesTable.hh>

Inheritance diagram for G4UCNMaterialPropertiesTable:

Public Member Functions
	G4UCNMaterialPropertiesTable ()

	~G4UCNMaterialPropertiesTable () override

G4double *	GetMicroRoughnessTable ()

G4double *	GetMicroRoughnessTransTable ()

void	LoadMicroRoughnessTables (G4double , G4double , G4double , G4double )

void	InitMicroRoughnessTables ()

void	ComputeMicroRoughnessTables ()

G4double	GetMRIntProbability (G4double, G4double)

G4double	GetMRMaxProbability (G4double, G4double)

void	SetMRMaxProbability (G4double, G4double, G4double)

G4double	GetMRProbability (G4double, G4double, G4double, G4double, G4double)

G4double	GetMRIntTransProbability (G4double, G4double)

G4double	GetMRMaxTransProbability (G4double, G4double)

void	SetMRMaxTransProbability (G4double, G4double, G4double)

G4double	GetMRTransProbability (G4double, G4double, G4double, G4double, G4double)

G4bool	ConditionsValid (G4double E, G4double VFermi, G4double theta_i)

G4bool	TransConditionsValid (G4double E, G4double VFermi, G4double theta_i)

void	SetMicroRoughnessParameters (G4double, G4double, G4int, G4int, G4double, G4double, G4double, G4double, G4int, G4int, G4double)

G4double	GetRMS () const

G4double	GetCorrLen () const

Public Member Functions inherited from G4MaterialPropertiesTable
	G4MaterialPropertiesTable ()

virtual	~G4MaterialPropertiesTable ()

void	AddConstProperty (const G4String &key, G4double propertyValue, G4bool createNewKey=false)

void	AddConstProperty (const char *key, G4double propertyValue, G4bool createNewKey=false)

G4MaterialPropertyVector *	AddProperty (const G4String &key, const std::vector< G4double > &photonEnergies, const std::vector< G4double > &propertyValues, G4bool createNewKey=false, G4bool spline=false)

G4MaterialPropertyVector *	AddProperty (const char key, G4double photonEnergies, G4double *propertyValues, G4int numEntries, G4bool createNewKey=false, G4bool spline=false)

void	AddProperty (const G4String &key, G4MaterialPropertyVector *opv, G4bool createNewKey=false)

void	AddProperty (const char key, G4MaterialPropertyVector opv, G4bool createNewKey=false)

void	AddProperty (const G4String &key, const G4String &mat)

void	RemoveConstProperty (const G4String &key)

void	RemoveConstProperty (const char *key)

void	RemoveProperty (const G4String &key)

void	RemoveProperty (const char *key)

G4double	GetConstProperty (const G4String &key) const

G4double	GetConstProperty (const char *key) const

G4double	GetConstProperty (const G4int index) const

G4bool	ConstPropertyExists (const G4String &key) const

G4bool	ConstPropertyExists (const char *key) const

G4bool	ConstPropertyExists (const G4int index) const

G4MaterialPropertyVector *	GetProperty (const char *key) const

G4MaterialPropertyVector *	GetProperty (const G4String &key) const

G4MaterialPropertyVector *	GetProperty (const G4int index) const

void	AddEntry (const G4String &key, G4double aPhotonEnergy, G4double aPropertyValue)

void	AddEntry (const char *key, G4double aPhotonEnergy, G4double aPropertyValue)

G4int	GetConstPropertyIndex (const G4String &key) const

G4int	GetPropertyIndex (const G4String &key) const

void	DumpTable () const

const std::vector< G4String > &	GetMaterialPropertyNames () const

const std::vector< G4String > &	GetMaterialConstPropertyNames () const

const std::vector< G4MaterialPropertyVector * > &	GetProperties () const

const std::vector< std::pair< G4double, G4bool > > &	GetConstProperties () const

Detailed Description

Definition at line 50 of file G4UCNMaterialPropertiesTable.hh.

Constructor & Destructor Documentation

◆ G4UCNMaterialPropertiesTable()

G4UCNMaterialPropertiesTable::G4UCNMaterialPropertiesTable ( )

Definition at line 53 of file G4UCNMaterialPropertiesTable.cc.

{
  theMicroRoughnessTable = nullptr;
  maxMicroRoughnessTable = nullptr;
  theMicroRoughnessTransTable = nullptr;
  maxMicroRoughnessTransTable = nullptr;
 
  theta_i_min = 0. * degree;
  theta_i_max = 90. * degree;
 
  Emin = 0.e-9 * eV;
  Emax = 1000.e-9 * eV;
 
  no_theta_i = 90;
  noE = 100;
 
  theta_i_step = (theta_i_max - theta_i_min) / (no_theta_i - 1);
  E_step = (Emax - Emin) / (noE - 1);
 
  b = 1 * nm;
  w = 30 * nm;
 
  AngCut = 0.01 * degree;
}

◆ ~G4UCNMaterialPropertiesTable()

G4UCNMaterialPropertiesTable::~G4UCNMaterialPropertiesTable ( )

override

Definition at line 78 of file G4UCNMaterialPropertiesTable.cc.

{
  delete theMicroRoughnessTable;
  delete maxMicroRoughnessTable;
  delete theMicroRoughnessTransTable;
  delete maxMicroRoughnessTransTable;
}

Member Function Documentation

◆ ComputeMicroRoughnessTables()

void G4UCNMaterialPropertiesTable::ComputeMicroRoughnessTables ( )

Definition at line 135 of file G4UCNMaterialPropertiesTable.cc.

{
  // Reads the parameters for the mr-probability computation from the
  // corresponding material properties and stores it in the appropriate
  // variables
 
  b = GetConstProperty("MR_RRMS");
  G4double b2 = b * b;
  w = GetConstProperty("MR_CORRLEN");
  G4double w2 = w * w;
 
  no_theta_i = G4int(GetConstProperty("MR_NBTHETA") + 0.1);
  noE = G4int(GetConstProperty("MR_NBE") + 0.1);
 
  theta_i_min = GetConstProperty("MR_THETAMIN");
  theta_i_max = GetConstProperty("MR_THETAMAX");
  Emin = GetConstProperty("MR_EMIN");
  Emax = GetConstProperty("MR_EMAX");
  auto AngNoTheta = G4int(GetConstProperty("MR_ANGNOTHETA") + 0.1);
  auto AngNoPhi = G4int(GetConstProperty("MR_ANGNOPHI") + 0.1);
  AngCut = GetConstProperty("MR_ANGCUT");
 
  // The Fermi potential was saved in neV by P.F.
 
  G4double fermipot = GetConstProperty("FERMIPOT") * (1.e-9 * eV);
 
  G4double theta_i, E;
 
  // Calculates the increment in theta_i in the lookup-table
  theta_i_step = (theta_i_max - theta_i_min) / (no_theta_i - 1);
 
  // Calculates the increment in energy in the lookup-table
  E_step = (Emax - Emin) / (noE - 1);
 
  // Runs the lookup-table memory allocation
  InitMicroRoughnessTables();
 
  G4int counter = 0;
 
  // Writes the mr-lookup-tables to files for immediate control
  std::ofstream dateir("MRrefl.dat", std::ios::out);
  std::ofstream dateit("MRtrans.dat", std::ios::out);
 
  // G4cout << theMicroRoughnessTable << G4endl;
 
  for (theta_i = theta_i_min; theta_i <= theta_i_max + 1e-6; theta_i += theta_i_step) {
    // Calculation for each cell in the lookup-table
    for (E = Emin; E <= Emax; E += E_step) {
      *(theMicroRoughnessTable + counter) = G4UCNMicroRoughnessHelper::GetInstance()->IntIplus(E,
        fermipot, theta_i, AngNoTheta, AngNoPhi, b2, w2, maxMicroRoughnessTable + counter, AngCut);
 
      *(theMicroRoughnessTransTable + counter) =
        G4UCNMicroRoughnessHelper::GetInstance()->IntIminus(E, fermipot, theta_i, AngNoTheta,
          AngNoPhi, b2, w2, maxMicroRoughnessTransTable + counter, AngCut);
 
      dateir << *(theMicroRoughnessTable + counter) << G4endl;
      dateit << *(theMicroRoughnessTransTable + counter) << G4endl;
 
      counter++;
    }
  }
 
  dateir.close();
  dateit.close();
 
  // Writes the mr-lookup-tables to files for immediate control
 
  std::ofstream dateic("MRcheck.dat", std::ios::out);
  std::ofstream dateimr("MRmaxrefl.dat", std::ios::out);
  std::ofstream dateimt("MRmaxtrans.dat", std::ios::out);
 
  for (theta_i = theta_i_min; theta_i <= theta_i_max + 1e-6; theta_i += theta_i_step) {
    for (E = Emin; E <= Emax; E += E_step) {
      // tests the GetXXProbability functions by writing the entries
      // of the lookup tables to files
 
      dateic << GetMRIntProbability(theta_i, E) << G4endl;
      dateimr << GetMRMaxProbability(theta_i, E) << G4endl;
      dateimt << GetMRMaxTransProbability(theta_i, E) << G4endl;
    }
  }
 
  dateic.close();
  dateimr.close();
  dateimt.close();
}

Referenced by SetMicroRoughnessParameters().

◆ ConditionsValid()

G4bool G4UCNMaterialPropertiesTable::ConditionsValid	(	G4double	E,
		G4double	VFermi,
		G4double	theta_i )

Definition at line 377 of file G4UCNMaterialPropertiesTable.cc.

{
  G4double k = std::sqrt(2 * neutron_mass_c2 * E / hbarc_squared);
  G4double k_l = std::sqrt(2 * neutron_mass_c2 * VFermi / hbarc_squared);
 
  // see eq. 17 of the Steyerl paper
  return 2 * b * k * std::cos(theta_i) < 1 && 2 * b * k_l < 1;
}

◆ GetCorrLen()

G4double G4UCNMaterialPropertiesTable::GetCorrLen ( ) const

inline

Definition at line 171 of file G4UCNMaterialPropertiesTable.hh.

171{ return w; }

◆ GetMicroRoughnessTable()

G4double * G4UCNMaterialPropertiesTable::GetMicroRoughnessTable ( )

Definition at line 86 of file G4UCNMaterialPropertiesTable.cc.

86{ return theMicroRoughnessTable; }

◆ GetMicroRoughnessTransTable()

G4double * G4UCNMaterialPropertiesTable::GetMicroRoughnessTransTable ( )

Definition at line 88 of file G4UCNMaterialPropertiesTable.cc.

{
  return theMicroRoughnessTransTable;
}

◆ GetMRIntProbability()

G4double G4UCNMaterialPropertiesTable::GetMRIntProbability	(	G4double	theta_i,
		G4double	Energy )

Definition at line 222 of file G4UCNMaterialPropertiesTable.cc.

{
  if (theMicroRoughnessTable == nullptr) {
    G4cout << "Do not have theMicroRoughnessTable" << G4endl;
    return 0.;
  }
 
  // if theta_i or energy outside the range for which the lookup table is
  // calculated, the probability is set to zero
  if (theta_i < theta_i_min || theta_i > theta_i_max || Energy < Emin || Energy > Emax) {
    return 0.;
  }
 
  // Determines the nearest cell in the lookup table which contains
  // the probability
 
  auto theta_i_pos = G4int((theta_i - theta_i_min) / theta_i_step + 0.5);
  auto E_pos = G4int((Energy - Emin) / E_step + 0.5);
 
  // lookup table is onedimensional (1 row), energy is in rows,
  // theta_i in columns
  return *(theMicroRoughnessTable + E_pos + theta_i_pos * (noE - 1));
}

Referenced by ComputeMicroRoughnessTables().

◆ GetMRIntTransProbability()

G4double G4UCNMaterialPropertiesTable::GetMRIntTransProbability	(	G4double	theta_i,
		G4double	Energy )

Definition at line 246 of file G4UCNMaterialPropertiesTable.cc.

{
  if (theMicroRoughnessTransTable == nullptr) {
    return 0.;
  }
 
  // if theta_i or energy outside the range for which the lookup table
  // is calculated, the probability is set to zero
 
  if (theta_i < theta_i_min || theta_i > theta_i_max || Energy < Emin || Energy > Emax) {
    return 0.;
  }
 
  // Determines the nearest cell in the lookup table which contains
  // the probability
 
  auto theta_i_pos = G4int((theta_i - theta_i_min) / theta_i_step + 0.5);
  auto E_pos = G4int((Energy - Emin) / E_step + 0.5);
 
  // lookup table is onedimensional (1 row), energy is in rows,
  // theta_i in columns
 
  return *(theMicroRoughnessTransTable + E_pos + theta_i_pos * (noE - 1));
}

◆ GetMRMaxProbability()

G4double G4UCNMaterialPropertiesTable::GetMRMaxProbability	(	G4double	theta_i,
		G4double	Energy )

Definition at line 271 of file G4UCNMaterialPropertiesTable.cc.

{
  if (maxMicroRoughnessTable == nullptr) {
    return 0.;
  }
 
  // if theta_i or energy outside the range for which the lookup table
  // is calculated, the probability is set to zero
 
  if (theta_i < theta_i_min || theta_i > theta_i_max || Energy < Emin || Energy > Emax) {
    return 0.;
  }
 
  // Determines the nearest cell in the lookup table which contains
  // the probability
 
  auto theta_i_pos = G4int((theta_i - theta_i_min) / theta_i_step + 0.5);
  auto E_pos = G4int((Energy - Emin) / E_step + 0.5);
 
  // lookup table is onedimensional (1 row), energy is in rows,
  // theta_i in columns
 
  return *(maxMicroRoughnessTable + E_pos + theta_i_pos * noE);
}

Referenced by ComputeMicroRoughnessTables().

◆ GetMRMaxTransProbability()

G4double G4UCNMaterialPropertiesTable::GetMRMaxTransProbability	(	G4double	theta_i,
		G4double	Energy )

Definition at line 317 of file G4UCNMaterialPropertiesTable.cc.

{
  if (maxMicroRoughnessTransTable == nullptr) {
    return 0.;
  }
 
  // if theta_i or energy outside the range for which the lookup table
  // is calculated, the probability is set to zero
 
  if (theta_i < theta_i_min || theta_i > theta_i_max || Energy < Emin || Energy > Emax) {
    return 0.;
  }
 
  // Determines the nearest cell in the lookup table which contains
  // the probability
 
  auto theta_i_pos = G4int((theta_i - theta_i_min) / theta_i_step + 0.5);
  auto E_pos = G4int((Energy - Emin) / E_step + 0.5);
 
  // lookup table is onedimensional (1 row), energy is in rows,
  // theta_i in columns
 
  return *(maxMicroRoughnessTransTable + E_pos + theta_i_pos * noE);
}

Referenced by ComputeMicroRoughnessTables().

◆ GetMRProbability()

G4double G4UCNMaterialPropertiesTable::GetMRProbability	(	G4double	theta_i,
		G4double	Energy,
		G4double	fermipot,
		G4double	theta_o,
		G4double	phi_o )

Definition at line 363 of file G4UCNMaterialPropertiesTable.cc.

{
  return G4UCNMicroRoughnessHelper::GetInstance()->ProbIplus(
    Energy, fermipot, theta_i, theta_o, phi_o, b, w, AngCut);
}

◆ GetMRTransProbability()

G4double G4UCNMaterialPropertiesTable::GetMRTransProbability	(	G4double	theta_i,
		G4double	Energy,
		G4double	fermipot,
		G4double	theta_o,
		G4double	phi_o )

Definition at line 370 of file G4UCNMaterialPropertiesTable.cc.

{
  return G4UCNMicroRoughnessHelper::GetInstance()->ProbIminus(
    Energy, fermipot, theta_i, theta_o, phi_o, b, w, AngCut);
}

◆ GetRMS()

G4double G4UCNMaterialPropertiesTable::GetRMS ( ) const

inline

Definition at line 170 of file G4UCNMaterialPropertiesTable.hh.

170{ return b; }

◆ InitMicroRoughnessTables()

void G4UCNMaterialPropertiesTable::InitMicroRoughnessTables ( )

Definition at line 103 of file G4UCNMaterialPropertiesTable.cc.

{
  G4int NEdim = 0;
  G4int Nthetadim = 0;
 
  // Checks if the number of angles is available and stores it
 
  if (ConstPropertyExists("MR_NBTHETA")) {
    Nthetadim = G4int(GetConstProperty("MR_NBTHETA") + 0.1);
  }
 
  // Checks if the number of energies is available and stores it
 
  if (ConstPropertyExists("MR_NBE")) {
    NEdim = G4int(GetConstProperty("MR_NBE") + 0.1);
  }
 
  // If both dimensions of the lookup-table are non-trivial:
  // delete old tables if existing and allocate memory for new tables
 
  if (Nthetadim * NEdim > 0) {
    delete theMicroRoughnessTable;
    theMicroRoughnessTable = new G4double[Nthetadim * NEdim];
    delete maxMicroRoughnessTable;
    maxMicroRoughnessTable = new G4double[Nthetadim * NEdim];
    delete theMicroRoughnessTransTable;
    theMicroRoughnessTransTable = new G4double[Nthetadim * NEdim];
    delete maxMicroRoughnessTransTable;
    maxMicroRoughnessTransTable = new G4double[Nthetadim * NEdim];
  }
}

Referenced by ComputeMicroRoughnessTables().

◆ LoadMicroRoughnessTables()

void G4UCNMaterialPropertiesTable::LoadMicroRoughnessTables	(	G4double *	pMicroRoughnessTable,
		G4double *	pmaxMicroRoughnessTable,
		G4double *	pMicroRoughnessTransTable,
		G4double *	pmaxMicroRoughnessTransTable )

Definition at line 93 of file G4UCNMaterialPropertiesTable.cc.

{
  theMicroRoughnessTable = pMicroRoughnessTable;
  maxMicroRoughnessTable = pmaxMicroRoughnessTable;
  theMicroRoughnessTransTable = pMicroRoughnessTransTable;
  maxMicroRoughnessTransTable = pmaxMicroRoughnessTransTable;
}

◆ SetMicroRoughnessParameters()

void G4UCNMaterialPropertiesTable::SetMicroRoughnessParameters	(	G4double	ww,
		G4double	bb,
		G4int	no_theta,
		G4int	no_E,
		G4double	theta_min,
		G4double	theta_max,
		G4double	E_min,
		G4double	E_max,
		G4int	AngNoTheta,
		G4int	AngNoPhi,
		G4double	AngularCut )

Definition at line 402 of file G4UCNMaterialPropertiesTable.cc.

{
  // Removes an existing RMS roughness
  if (ConstPropertyExists("MR_RRMS")) {
    RemoveConstProperty("MR_RRMS");
  }
 
  // Adds a new RMS roughness
  AddConstProperty("MR_RRMS", bb);
 
  // Removes an existing correlation length
  if (ConstPropertyExists("MR_CORRLEN")) {
    RemoveConstProperty("MR_CORRLEN");
  }
 
  // Adds a new correlation length
  AddConstProperty("MR_CORRLEN", ww);
 
  // Removes an existing number of thetas
  if (ConstPropertyExists("MR_NBTHETA")) {
    RemoveConstProperty("MR_NBTHETA");
  }
 
  // Adds a new number of thetas
  AddConstProperty("MR_NBTHETA", (G4double)no_theta);
 
  // Removes an existing number of Energies
  if (ConstPropertyExists("MR_NBE")) {
    RemoveConstProperty("MR_NBE");
  }
 
  // Adds a new number of Energies
  AddConstProperty("MR_NBE", (G4double)no_E);
 
  // Removes an existing minimum theta
  if (ConstPropertyExists("MR_THETAMIN")) {
    RemoveConstProperty("MR_THETAMIN");
  }
 
  // Adds a new minimum theta
  AddConstProperty("MR_THETAMIN", theta_min);
 
  // Removes an existing maximum theta
  if (ConstPropertyExists("MR_THETAMAX")) {
    RemoveConstProperty("MR_THETAMAX");
  }
 
  // Adds a new maximum theta
  AddConstProperty("MR_THETAMAX", theta_max);
 
  // Removes an existing minimum energy
  if (ConstPropertyExists("MR_EMIN")) {
    RemoveConstProperty("MR_EMIN");
  }
 
  // Adds a new minimum energy
  AddConstProperty("MR_EMIN", E_min);
 
  // Removes an existing maximum energy
  if (ConstPropertyExists("MR_EMAX")) {
    RemoveConstProperty("MR_EMAX");
  }
 
  // Adds a new maximum energy
  AddConstProperty("MR_EMAX", E_max);
 
  // Removes an existing Theta angle number
  if (ConstPropertyExists("MR_ANGNOTHETA")) {
    RemoveConstProperty("MR_ANGNOTHETA");
  }
 
  // Adds a new Theta angle number
  AddConstProperty("MR_ANGNOTHETA", (G4double)AngNoTheta);
 
  // Removes an existing Phi angle number
  if (ConstPropertyExists("MR_ANGNOPHI")) {
    RemoveConstProperty("MR_ANGNOPHI");
  }
 
  // Adds a new Phi angle number
  AddConstProperty("MR_ANGNOPHI", (G4double)AngNoPhi);
 
  // Removes an existing angular cut
  if (ConstPropertyExists("MR_ANGCUT")) {
    RemoveConstProperty("MR_ANGCUT");
  }
 
  // Adds a new angle number
  AddConstProperty("MR_ANGCUT", AngularCut);
 
  // Starts the lookup table calculation
  ComputeMicroRoughnessTables();
}

◆ SetMRMaxProbability()

void G4UCNMaterialPropertiesTable::SetMRMaxProbability	(	G4double	theta_i,
		G4double	Energy,
		G4double	value )

Definition at line 296 of file G4UCNMaterialPropertiesTable.cc.

{
  if (maxMicroRoughnessTable != nullptr) {
    if (theta_i < theta_i_min || theta_i > theta_i_max || Energy < Emin || Energy > Emax) {
    }
    else {
      // Determines the nearest cell in the lookup table which contains
      // the probability
 
      auto theta_i_pos = G4int((theta_i - theta_i_min) / theta_i_step + 0.5);
      auto E_pos = G4int((Energy - Emin) / E_step + 0.5);
 
      // lookup table is onedimensional (1 row), energy is in rows,
      // theta_i in columns
 
      *(maxMicroRoughnessTable + E_pos + theta_i_pos * noE) = value;
    }
  }
}

◆ SetMRMaxTransProbability()

void G4UCNMaterialPropertiesTable::SetMRMaxTransProbability	(	G4double	theta_i,
		G4double	Energy,
		G4double	value )

Definition at line 342 of file G4UCNMaterialPropertiesTable.cc.

{
  if (maxMicroRoughnessTransTable != nullptr) {
    if (theta_i < theta_i_min || theta_i > theta_i_max || Energy < Emin || Energy > Emax) {
    }
    else {
      // Determines the nearest cell in the lookup table which contains
      // the probability
 
      auto theta_i_pos = G4int((theta_i - theta_i_min) / theta_i_step + 0.5);
      auto E_pos = G4int((Energy - Emin) / E_step + 0.5);
 
      // lookup table is onedimensional (1 row), energy is in rows,
      // theta_i in columns
 
      *(maxMicroRoughnessTransTable + E_pos + theta_i_pos * noE) = value;
    }
  }
}

◆ TransConditionsValid()

G4bool G4UCNMaterialPropertiesTable::TransConditionsValid	(	G4double	E,
		G4double	VFermi,
		G4double	theta_i )

Definition at line 386 of file G4UCNMaterialPropertiesTable.cc.

{
  G4double k2 = 2 * neutron_mass_c2 * E / hbarc_squared;
  G4double k_l2 = 2 * neutron_mass_c2 * VFermi / hbarc_squared;
 
  if (E * (std::cos(theta_i) * std::cos(theta_i)) < VFermi) {
    return false;
  }
 
  G4double kS2 = k_l2 - k2;
 
  // see eq. 18 of the Steyerl paper
  return 2 * b * std::sqrt(kS2) * std::cos(theta_i) < 1 && 2 * b * std::sqrt(k_l2) < 1;
}

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

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ G4UCNMaterialPropertiesTable()

◆ ~G4UCNMaterialPropertiesTable()

Member Function Documentation

◆ ComputeMicroRoughnessTables()

◆ ConditionsValid()

◆ GetCorrLen()

◆ GetMicroRoughnessTable()

◆ GetMicroRoughnessTransTable()

◆ GetMRIntProbability()

◆ GetMRIntTransProbability()

◆ GetMRMaxProbability()

◆ GetMRMaxTransProbability()

◆ GetMRProbability()

◆ GetMRTransProbability()

◆ GetRMS()

◆ InitMicroRoughnessTables()

◆ LoadMicroRoughnessTables()

◆ SetMicroRoughnessParameters()

◆ SetMRMaxProbability()

◆ SetMRMaxTransProbability()

◆ TransConditionsValid()