Advanced Instructions for NON-SMOKER^WEB

Custom input file

Advanced options:

The sections ENERGY_GRID and OPTIONS in the NON-SMOKER^web input file offer additional flexibility for the experienced user. Use these options with care. You should know what you are doing because changing the default options will offer the possibility to extract additional information while altering (and obscuring) the output of other information at the same time. All options not explicitly set will assume their default values. Without these sections all those options will have the default. Specifying an empty section (i.e. section headers present but no options set within) is not allowed but a whole section can be left out (this is done in the sample input file). For a sample with all sections, see the full input file.

• Detailed description:
  • Energy grid:
    • Section label: ENERGY_GRID
    • If this section is not present, NON-SMOKER^web automatically chooses an energy grid of (c.m.) projectile energies which is best suited for integrating the cross sections to obtain the astrophysical reaction rates for the used temperature grid. For instance, a denser grid is used around channel openings where the cross section fluctuates more. When one is only interested in comparing experimental and theoretical cross sections, then it is sometimes better to use a simpler energy grid. When this option is in effect, the code first uses its internal grid for the calculation and then interpolates the results to obtain the values on the specified grid.
      There are two ways to specify different energy grids which are selected by the labels EXPLICIT and GRID, respectively. Those option labels have to appear before the first data in this section.
    • Option EXPLICIT: Energies are given explicitly, one per line, in MeV. Up to 100 energies can be given, if there are more, then the excess values will be ignored.
    • Option GRID: Specification of an energy grid. The order of supplied values is en_start en_step (both in MeV). There can only be one line of this kind.
    • Options EXPLICIT and GRID cannot be mixed.
    • Note 1: Be careful when plotting these results! When your step width is too large you may miss certain features of the cross sections (such as fluctuations due to channel openings)! Make sure your step width catches all interesting features. The best is to first make a calculation without this option to identify the energy regions which have to be handled with care.
    • Note 2: The S-factors are computed from the original result and then also interpolated (separately from the cross sections). Therefore, there may be small numerical differences between the cross section and its corresponding S-factor at a given energy compared to the "true" S-factor for that cross section.
    • Getting the result page may take longer with this option because the code has to finish all calculations before the interpolation is performed.
  • Further options:
    • Section label: OPTIONS
    • A number of options can be set which affect the results and/or output format. This is only for specialists! Some of the options take 1, 2, or 3 integer parameters which have to be given on the same line as the label. Note that you must not combine these options with choosing a target range! The results might be incorrect.

      Currently recognized options include:

      • MASSOPT
        • # of parameters: 1 (switch: 0...2)

        • Determines how the masses are used to compute the separation energies (Q-values).

          0: (Default)Experimental masses are taken whenever available, theoretical masses otherwise. However, different masses are not mixed. If there is at least one unknown mass in any of the considered reaction channels, only theoretical masses are taken even when the experimental value is known for a nucleus.
          1: Always just use theoretical masses.
          2: Always uses experimental masses when known even if mixing of theory and experiment occurs.

          Note: This option only affects how Q-values are computed, it does not affect the level density.
      • EQUIVPOT
        • # of parameters: 1 (switch: 0...1)
        • Only affecting potentials read from external file: Use deformed potential.
          When this option is set the spherical potential is transformed into an "equivalent potential" according to the deformation parameter.
          Default value is 1.
      • TEMPGRID
        • # of parameters: 1 (switch: 0...4)
        • Redefine temperature grid for the astrophysical reaction rates. Default value is 0. If the MACS are printed, some of them might be incorrect.
      • DEFORM
        • # of parameters: 2 (switch: 0...1, # of lines: 1...4)
        • Specify deformations (other than the default ones) for the different channels. The specified deformations are only used if switch>0 (default is 0). The second parameter specifies how many lines with deformation are following.
        • This option has to be followed by lines specifying channel and deformation, according to the # of lines given above. The lines have the format '* n x', where '*' can be any of the characters n, p, a, c, 'n' is a switch (0...off (default) or 1...on), and 'x' is the deformation beta2. The character at the beginning of the line specifies to which channel/nucleus the given deformation is applied: c...compound nucleus, n...compound-n, p...compound-p, a...compound-alpha.
        • Example of a valid entry:
          

          #*DEFORM 1 3
          c 1 0.283
          n 0 0.100
          a 1 -0.2

          In the above definition the deformations for the compound nucleus and the compound minus alpha channel are explicitly given. For the compound minus neutron and compound minus proton (not explicitly given here) channel the default deformations are used.
      • GDR
        • # of parameters: 2 (switch: 0...1, # of lines: 1...2)
        • Specification of GDR parameters when switch=1 (default is Zero). The second parameter specifies how many lines with GDR parameters are following.
        • Without this option or with switch=0, the theoretical description by Thielemann & Arnould 1983 is used (with a low energy modification, see below).
        • This option line has to be followed by one or two (according to the second parameter) lines, each giving a GDR energy and width in MeV. These are the values used for computing the E1 strength in the calculation. If only one line is given, the same values are applied to the GDR part parallel and perpendicular to the axis of symmetry, thus treating the GDR as undeformed (even when the nucleus is deformed). With two lines, the first line gives the energy and width for the parallel collective motion (z) and the second line the ones for the perpendicular motion (xy). (With the switch set to Zero, the values are read in but not used; instead the default GDR parameters (e.g., as specified with option E1TRANS) are used, which are calculated internally.)
        • Note that the GDR used here is not a simple Lorentzian but has a modified energy dependence at low energies. This modification of the low-energy tail of the GDR is also used when the parameters are specified with this option.
        • Example:
          

          #*GDR 1 2
          16.22 5.29
          16.22 5.29

      • WIDTHS
        • # of parameters: 2 (switch: -2...2, spin: -24...24)
        • Default value of switch is 0 (do nothing). When switch<>0: Print averaged widths or strength functions, respectively, for compound states with the given spin/parity. The spin is given in multiples of 0.5, the parity is derived from the sign of the spin parameter. Thus, a value of -3 denotes a 3/2- state. The values are printed for all energies defined by the used energy grid.
          Averaged neutron, proton, alpha, and gamma-widths are printed when the switch is set to +/-1. Strengths are printed with switch=+/-2. For an explanation of the difference of using positive and negative values, see the next item.
        • For direct comparison with experiment it is recommended to use strengths, not widths. Averaged widths are connected to the strength functions via the nuclear level density, whereas strengths are directly proportional to the potential transmission coefficients internally used in NON-SMOKER^web. This is important, for instance, when checking the accuracy of optical potentials against strength functions directly derived from experiment (see PRC 69 (2004) 015803). Another important point when comparing to experimental widths or strength is the impact of the width fluctuation corrections. Those corrections have to be applied when calculating reactions and are therefore used in NON-SMOKER^web. For further details, see the above reference and the NON-SMOKER references given elsewhere. However, when comparing to experiment or when publishing resonance data, it is sometimes preferrable to quote the pure widths and strengths, so that corrections can be applied later when necessary.
          When specifying switch=1,2 the width fluctuation corrections are switched off. With switch=-1,-2 the width fluctuation corrections will not be forced to be switched off but rather will be on (default) or off (when option WFC is given with parameter 0, see below).
        • The widths/strength functions are printed for the compound nucleus, i.e. the nucleus made from target+projectile, for the given spin and parity!
        • Note that there is a separate column for the entrance channel. The entrance channel column gives the width of the transition to the ground state of the target nucleus, which enters the calculation of the cross section. The other columns show widths summed over all possible transitions.
        • For neutrons, also the reduced neutron width and the reduced strength, respectively, are given. Those values are obtained by dividing the neutron width and strength, respectively, by the square root of the neutron energy in eV.
      • WFC
        • # of parameters: 1 (switch: 0...1)
        • Switch width fluctuation corrections on (switch=1) and off (switch=0). Default is on.
      • E2TRANS
        • # of parameters: 1 (switch: 0...1)
        • Switch E2 transitions on (switch=1) and off (switch=0) in the calculation of the gamma-transitions. Default is on.
      • E1TRANS
        • # of parameters: 1 (switch: 1...6)
        • Determines the treatment of the E1 component of the gamma-widths:
          1. Holmes et al. (1976)
          2. Johnson et al. (1977)
          3. Thielemann & Arnould (1983)
          4. like 3 but additionally add pygmy resonance (note: this option depends on the treatment of the pygmy resonance currently hardwired in the code and is not applicable to all nuclei; use of this value is strongly discouraged)
          5. GDR energies from P. Van Isacker et al. (1992), Phys. Rev. C45, R13; widths calculated as for 3 but with nuclear properties from ETFSI-2 model (as provided in RIPL-2). Note: Combining this option with PRINTINFO will not show the correct deformation value!
          6. (Default)like 3 but with experimental GDR energies and widths (from RIPL-2), if known
      • ISO
        • # of parameters: 1 (switch: 0...3)

        • Treatment of isospin mixing; it is recommended not to use this option unless you have a very good reason. Currently allowed values:

          0: Complete isospin mixing (neglect isospin)
          1: Complete isospin mixing but use Woosley et al. suppression factors for gamma width
          2: (Default) Complete isospin mixing but use Rauscher suppression of gamma width
          3: Incomplete isospin mixing (not tested for web use)
          4: Incomplete isospin mixing with explicit constant mixing parameter (under construction!)

      • SPECTRANS
        • # of parameters: 3 (switch: 0...4, level_target: 1...(xx), level_exit: 1...(xx))
        • Selects a specific transition to be calculated (usually, a sum over all energetically possible transitions is executed). With switch=1-4 the reaction channel is selected (gamma (1), neutron (2), proton (3), alpha (4) channel). The parameter level_target selects the level in the target from which the reaction proceeds and level_exit accordingly specifies the state in the final nucleus in the exit channel chosen with switch. Counting starts with 1 being the ground state, 2 being the first excited state, etc. Predictable results can only be obtained when the addressed states were explicitly input, e.g. by using the section EXCITED_STATES in the input file. A maximum of xx levels (including g.s.) can be specified there, depending on the code version you are using.
        • The setting of level_target impacts the calculation even when switch=0! The specified level is treated as the ground state of the target! (The value of level_exit is not used when switch=0).
        • Default values are switch=0, level_target=1, level_exit=1.
      • PRINTINFO
        • # of parameters: 1 (switch=0...1)
        • Prints some internal values and stops when set to 1. By default, this switch is set to Zero.

        • The information printed contains the following:

          • Separation energies in the compound nucleus (in MeV)
          • GDR energy and width in compound nucleus (in MeV); for deformed nuclei, the GDR resonance is split and the values along the symmetry axis (z) will be different from the ones perpendicular to it (xy).
          • For each of the four involved nuclei:
          • EX: can be 1 or 0. A 1 indicates that the mass was taken from experiment, a Zero indicates a theoretical value (the meaning of this depends on the chosen mass treatment).
          • BET: Deformation (beta-Parameter)
          • A: Level density parameter in MeV^-1; when an energy dependent parameter is used, the value at 10 MeV excitation energy is given.
          • DELTA: Backshift of the Fermi-Gas in MeV
          • T: Matching temperature of constant temperature formula
          • E0: Matching energy of constant temperature formula
          • Excited states: The discrete excited states used in the calculation. These are either from experiment or from additional input. Shown is the excitation energy in MeV, the spin, and the parity.

      • CUTOFF
        • # of parameters: 1 (switch=0...2)

        • For experts: Cutoff of the gamma width according to its relation to the total width; default value is 1. This is especially important when studying alpha-induced reactions with negative Q-value.

          0: cutoff set as in the old SMOKER code
          1: (Default) different cutoff threshold
          2: no cutoff

      • FISSION
        • # of parameters: 1 (switch=0...1)
        • Switch fission on (switch=1) or off (switch=0). Default is off.
        • Note: Even when switched on, a nucleus is only considered to be fissionable when there is an entry for fission barriers found in the fission data file! This data file includes the same nuclei as the one calculated by Howard & Moeller 1980 but barriers from a self-consistent Thomas-Fermi model (PRC 60 (1999) 014606) are used.
      • NUCDENS
        • # of parameters: 1 (switch=1...3)

        • Select nuclear density distribution used for determining nucleon densities and nuclear radii

          1: Local density approximation by Negele, PRC 1 (1970) 1260
          2: Droplet model
          3: (Default) HFB-02 from RIPL-2

      • NLDPARITY
        • # of parameters: 1 (switch=0...1)
        • Determines parity distribution in the nuclear level density as function of excitation energy.
        • Switch between equally distributed parities (switch=0) and the parity distribution by Mocelj et al. (2007) (switch=1). Default is the latter.
        • Note: The parity distribution chosen here (or the default one) is also used when specifying external parameters for the nuclear level density.
      • STATMOD
        • # of parameters: 1 (switch=0...2)

        • Selects the type of model used to calculate the cross sections and rates. The classical statistical model (Hauser-Feshbach) assumes that the compound nucleus is formed at sufficiently high excitation energy to exhibit all spins and parities. For most stable targets (except at magic numbers) this is a good assumption. However, for astrophysical purposes nuclides with low separation energies have to be considered, in which not all spins and parities are present at a given excitation energy. The (known or calculated) spin and parity distribution, however, can be used to weight the relevant transitions and to compute a suppression factor. This will lead to a suppression of Hauser-Feshbach cross sections for compound nuclei with low projectile separation energy. The value of STATMOD will result in the following behavior:

          0: (Default) Classical Hauser-Feshbach model (all spins and parities are assumed to occur in the compound nucleus)
          1: The compound cross section is weighted according to a parity distribution. Note: This is also affected by the choice in the NLDPARITY option and other options affecting the parity in the nuclear level density.
          2: Like 1 but additionally the distribution of the spins with excitation energy is also considered. Note: This is also affected by all options impacting the nuclear level density!
          3: (currently disabled) Suppression factor relative to a minimally required NLD

      • NLDFACT
        • # of parameters: 2 (switch=0...1, # of lines: 1...4)
        • Specify NLD multiplication factors for the different channels. The specified factors are only used if switch>0 (default is 0). The second parameter specifies how many lines with factors are following.
        • This option has to be followed by lines specifying channel and factors, according to the # of lines given above. The lines have the format '* n x', where '*' can be any of the characters n, p, a, c, 'n' is a switch (0...off (default) or 1...on), and 'x' is the NLD multiplication factor. The character at the beginning of the line specifies to which channel/nucleus the given factor is applied: c...compound nucleus, n...compound-n, p...compound-p, a...compound-alpha.
        • Example of a valid entry:
          

          #*NLDFACT 1 3
          c 1 2.2
          n 0 0.100
          a 1 0.2

          In the above definition the factors for the compound nucleus and the compound minus alpha channel are explicitly given. For the compound minus neutron and compound minus proton (not explicitly given here) channel no factor (i.e. factor=1.0) is used. Only the absolute value of a factor is taken, i.e. any minus sign is ignored.
      • WFACT
        • # of parameters: 2 (switch=0...1, # of lines: 1...4)
        • Multiplies chosen widths (transmission coefficients) by a chosen factor.
        • Specify width multiplication factors for the different channels. The specified factors are only used if switch>0 (default is 0). The second parameter specifies how many lines with factors are following.
        • This option has to be followed by lines specifying channel and factors, according to the # of lines given above. The lines have the format '* n x p s', where '*' can be any of the characters i, n, p, a, c/g, 'n' is a switch (0...off (default) or 1...on), and 'x' is the multiplication factor. The character at the beginning of the line specifies to which channel/nucleus the given factor is applied: c/g...gamma width, n...neutron width, p...proton width, a...alpha width, i...incident width (between target state MI, usually the ground state). The parity is defined by p which can assume values -1, 0, +1 (with 0 transitions from compound states with any parity are used). The spin J of the compound nucleus from which the transition occurs is given as integer value in s=2*J. If s<0, then all spins (regardless of the value of s) are affected and multiplied by the factor x, otherwise only transitions originating from a compound nucleus with given spin/parity are multiplied.
        • By mixing i and the other options, the transition from the target ground state can be multiplied by another factor than the transitions to the excited target states.
        • Example of a valid entry:
          

          #*WFACT 1 3
          g 1 2.2 0 -1
          n 0 0.100 1 -1
          a 1 0.2 -1 3

          In the above definition the factors for the gamma widths and the alpha widths are explicitly given. For the neutron and proton widths (not explicitly given here) channel no factor (i.e. factor=1.0) is used. Only the absolute value of a factor is taken, i.e. any minus sign in the multiplication factor is ignored.
      • FORCEGRID
        • # of parameters: 1 (switch=0...1)
        • Use grid specified by ENERGY_GRID also for the internal calculation and do not interpolate. Default is off.
        • This option has no effect when there is no ENERGY_GRID section present and enabled.
        • This option has to be used with care because it can impact the obtained results by changing the integration grid. This is especially true for capture reactions with negative Q-values or photodisintegration reactions in general.
      • COULOMBWF
        • # of parameters: 1 (switch=-1...2)

        • Select method to compute the Coulomb wavefunctions required for the determination of the transmission coefficients.

          -1: C. Bardin et al., Comp. Phys. Comm. 3 (1972) 73 (do not use, unstable!)
          0: Recursion method by W.R. Smith, Comp. Phys. Comm. 1 (1969) 106
          1: Steed's method as implemented by A. R. Barnett 1981
          2: (Default) Automatic selection of best method as implemented in DFCOUL

      • SENSITIVITY
        • # of parameters: 1 (switch: 0...1)
        • When switched on (switch=1, default is off), additional output is created, showing the estimated sensitivity to variation of the widths. An additional (required) line gives the desired variation factor f. All widths are consecutively divided and multiplied by the factor f and the sensitivity factors s are printed for each reaction. The sensitivity is defined as a real value with a possible range of 0≤s≤1, 0 means no change, 1 means full impact of a width variation. In other words, when a width is changed by a factor f the cross section will be changed by a factor (f-1)*s+1 (marked by '=' in the output) or a factor (1/f-1)*s+1) (marked by 'X').
        • The sensitivity given is an estimate obtained without performing additional variational calculations but rather by comparing the relative size of the widths. For accurate sensitivity studies it is recommended to use the option WFACT to actually vary widths. However, in many cases the estimate obtained here is quite accurate and sufficient.
        • Due to the used method it is not possible to estimate the impact of the variation of the width in the entrance channel. Therefore, the results for two assumptions are shown for the width appearing in the entrance channel: 1. The partial (g.s.) width W_entrance_gs is constant while the total width W_entrance_tot=W_entrance_gs+W_entrance_excitedstates is varied; 2. both, W_entrance_gs and W_entrance_tot, are varied by the same factor. Case 1 assumes that the total entrance width is dominated by transitions from/to excited target states whereas case 2 assumes that the total entrance width is determined by the transitions from the ground state. For low (astrophysically relevant) projectile energies, often (but not always) case 2 is the better assumption. For a more accurate determination of the sensitivity to a variation of the entrance channel width use the option WFACT.
        • Example:
          

          #*SENSITIVITY 1
          2.

          This prints an additional section, showing the sensitivities when the widths are varied one by one by the factors 0.5 and 2.
      • Additional options might be added to this section without further notice...
  • Final remarks
    • Do not forget to check your input file with the checker tool. However, that program does not check the validity of the options within the OPTIONS section!
    • Because of the complexity of the options and the sensitivity of the results to them, please check carefully what you are doing and do not hesitate to contact the author!

© Dr. Thomas Rauscher (email), last change 2009-Jan-8