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/gamma2Pi_Xsections [ Modules ]

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NAME

module gamma2Pi_Xsections

PURPOSE

Includes the cross sections for gamma Nucleon -> Nucleon Pion Pion processes.

AUTHOR

Oliver Buss DATE 28/09/2005

gamma2Pi_Xsections/gamma2Pi_xsections [ Namelists ]

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NAME

NAMELIST gamma_2Pi_xsections

PURPOSE

Includes:

gamma2Pi_Xsections/experimentalXsections [ Global module-variables ]

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SOURCE

  logical , save :: experimentalXsections=.true.

PURPOSE

  • If .true. then the Xsections are taken from the experiment
  • If .false. then the theoretical values are given

gamma2Pi_Xsections/init [ Functions ]

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NAME

subroutine init

PURPOSE

Read out job card to initialize module parameters.

gamma2Pi_Xsections/gamma2pi [ Subroutines ]

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NAME

subroutine gamma2pi(qnuk,srts,sig2pi,betaToLRF,mediumAtPosition,position)

PURPOSE

Calculation of 2 pion cross sections

INPUTS

  • integer :: qnuk -- charge of nucleon
  • real :: srts -- SQRT(s)

OUTPUT

  • sig2pi(0:3) Cross sections for gamma+nucleon->nucleon+2Pi production
  • sig2pi(1) -> nucleon piMinus piPlus
  • sig2pi(2) -> nucleon piPlus piNull or nucleon piMinus piNull
  • sig2pi(3) -> nucleon piNull piNull
  • sig2pi(0) -> Total Xsection into nucleon+2 Pions

NOTES

  • Threshold improvement by Pascal Muehlich
  • Units of cross sections : [10^-6 barn]

gamma2Pi_Xsections/gP_ProtonPiPlusPiMinus [ Functions ]

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NOTES

Reads out data file and uses a spline with it.

OUTPUT

  • real, optional :: minPlab,minSig ! plab and sigma of lowest lying data point in the data file

gamma2Pi_Xsections/gP_NeutronPiPlusPiNull [ Functions ]

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NOTES

Reads out data file and uses a spline with it.

OUTPUT

  • real, optional :: minPlab,minSig ! plab and sigma of lowest lying data point in the data file

gamma2Pi_Xsections/gP_ProtonPiNullPiNul [ Functions ]

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NOTES

Reads out data file and uses a spline with it.

OUTPUT

  • real, optional :: minPlab,minSig ! plab and sigma of lowest lying data point in the data file

gamma2Pi_Xsections/gN_NeutronPiPlusPiMinus [ Functions ]

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NOTES

Reads out data file and uses a spline with it.

OUTPUT

  • real, optional :: minPlab,minSig ! plab and sigma of lowest lying data point in the data file

gamma2Pi_Xsections/gN_ProtonPiMinusPiNull [ Functions ]

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NOTES

Reads out data file and uses a spline with it.

OUTPUT

  • real, optional :: minPlab,minSig ! plab and sigma of lowest lying data point in the data file

gamma2Pi_Xsections/gN_NeutronPiNullPiNull [ Functions ]

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NOTES

Reads out data file and uses a spline with it.

OUTPUT

  • real, optional :: minPlab,minSig ! plab and sigma of lowest lying data point in the data file

gamma2Pi_Xsections/thres2pi [ Subroutines ]

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NAME

subroutine thres2pi(srts,sigma,qnuk,inThresholdRegion)

NOTES

  • This subroutine provides a reasonable threshold behaviour for the two pion photoproduction cross sections. gamma nucleon -> nucleon+2pi

* Retrieves the lowest data point of all the parametrizations and fits a phase space curve to it.

AUTHOR

  • Oliver Buss

INPUTS

OUTPUT

  • real :: sigma(1:3) cross sections (1=double charged, 2= single charged, 3= pi^0 pi^0)

* logical, dimension(1:3), intent (out) :: inThresholdRegion 

   .true. if sqrt(s) is smaller than lowest data point in the channel (1=double charged, 2= single charged, 3= pi^0 pi^0)