The software package FILTER is intended for neutron spectrum shape calculations after a composed filter and also for determination of the neutron spectrum shape parameters of the created quasi-mono-energy neutron line. The software package FILTER was created and continues to be updated by O. Gritzay (Ukrainian Nuclear Data Center, Kyiv, Ukraine).

The FILTER package consists of code Filter (ver.8) and a specialized library, which contains the following information:

1. The files with the total neutron cross sections for a set of materials in the point-wise format and linear-linear interpolation low (3rd ENDF file format). Total list of these files now contains more than 100 units (see Appendix 1).

These cross sections were calculated using code packages PREPRO or NJOY together with the most updated Libraries of Evaluated Nuclear Data (LEND). Accuracy of linearization procedure was taken as 0.1%, the temperature of materials as 300K.

In necessary cases this list may be added with new cross section files. The names of files may be arbitrary (except the file defined in point 2), but the length has to be equal or less than 12 symbols, one of those is the point, the last three are the file extension.

2. File DENSITY.dat is the density of material (in g/cm3). This file is used when the filter component is specified in cm (length). In this case it is necessary to take in mind, that the names of the input cross section files have to be just the same as the names of elements in file DENSITY.dat. For instance, if the name of material in DENSITY.dat is 3LI07, then the file name for Lithium-7 cross section has to be the same, namely 3LI07.* (the file extension is allowed). In other case, one may receive the message about absence of information: DENSITY FOR (your element) IS ABSENT and the code will be stopped.

3. File HE3_NP contains an energy dependent cross-section for reaction 3He(n, p), calculated with the use of JENDL-3.3 library. The accuracy of linearization was 0.1%, the temperature was taken as 300K. This file is used to take into account the energy-dependent efficiency in the case, when He-3 counter is used for neutron registration.

4. File H1_NEL contains an energy-dependent cross-section of elastic scattering of neutrons on hydrogen, calculated using JENDL-3.3. The linearization accuracy was 0.1%, the temperature is 300 K. This file is required to take into account the energy-dependence efficiency in the case, when a hydrogen counter is used for neutron registration.

All files must be in the same directory as the Filter-8.exe program. Before the first start of the program, a sub-directory F_RES must be created where the results of the program will be recorded.

The task for the program can be entered through a keyboard or an input task file, by forwarding a keyboard (UNIT = 5) to the file using <. The name of an input task file is arbitrary, but it should not exceed 8 characters and should not contain extensions.

The name of an input task file is entered regardless of whether the task is entered from a keyboard or from a task file. It is this name with different extensions that is used to write various output files (they will be recorded in sub directories F_RES).

The sequence of setting parameters in a task file is given in the file FILTER_TAB_eng.pdf.

FILTER_TAB_eng.pdf

Line	Position	Parameter	Explanation
1	1	InpName	Name of input file Not more, than 8 symbols, extension is forbidden
2	1	LLL	= 0 – length of component in g/cm2 ( on default DEF)* = 1 – length of component in cm
	2	IDET	= 1 – Helium-3 counter = 2 – proton recoil counter ( DEF)
	3	INTFU	= 1 – output data are presented as histogram function (DEF) = 2 – output data are presented as linear-linear function
	4	ERR	Difference between energies of successive points (in eV), at which in the joint grid the points are considered as identical. On default ERR= 0.0001 eV.
	5	LSP	= 0 –Maxwellian - up to 0.1 eV, 1 / E - from 0.1 eV to 67 keV, fission spectrum above 67 keV ( DEF) = 1 – arbitrary spectrum, set by the user in the fileSPECTRUM (format: №p / n, Energy, F). The number of rows should not exceed 70 000, the law of interpolation between points is linear-linear.
3	1	NAMEFILE	Filename with the total neutron cross-section of the component. No more than 12 characters, 3 of which extensions. If NAMEFILE=/, end of the filter component list.
4	1	ANf	Length of the filter component.
	2	LOGS	= 0 – no output of the cross sections for this component (DEF) = 1 – the cross sections for this component output into sub-directory F_RES in form of 3 columns: N (number), energy (eV), cross section (barn). Name of the output file corresponds to the name of input file NAMEFILE, but extension always will be .dat Rows 3 and 4 may be repeated any times. To mark the end of the list, instead NAMEFILE needs to type /
K	1	AK	Value, to be multiplied on maximum (in the output spectrum), to define a level, below which the peaks in the output spectrum aren’t taken into consideration (see Appendix 2). On DEFault AK=0.0001.
K+1	1	AKE	Relative difference between the left and right boundaries of successive peaks below which these peaks are regarded as one peak (see Appendix 3 ). On DEFault AKЕ=0.012.
K+2	1	Iedit	= 0 – short record - output only merged peaks (DEF) = 1 – full record (output split and merged peaks) in the file F_RES\InpName.lst
K+3	1	Ichose	= 1 – output only function T*SPECTRUM = 2 – output two functions (DEF) T*SPECTRUM and T*SPECTRUM*Sigma_DET in the file F_RES\InpName.lst
K+4	1	Icomp	= 0 – no output (DEF) = 1 – output information for comparison in the file F_RES\InpName.cmp
K+5	1	Igroupie	= 0 – no output = 1 – output spectra after filter in the GROUPIE form in the files F_RES\InpName.ts1 in boundaries Fmax *AK F_RES\InpName.ts2 in boundaries 2.5%*SUM & 97.5%*SUM = 2 – output spectra after filter in the GROUPIE form in the files F_RES\InpName.Gxx in boundaries Fmax *AK, where xx – number of peak (from the merged spectra).
If Igroupie = 2
K+6	1	Npeak	Number of peaks for which the spectra after the filter for the GROUPIE form output in the files F_RES\InpName.Gxx in boundaries Fmax *AK. If you select Npeak = 0, then the spectra for all of the merged peaks will be output in the files F_RES\InpName.Gxx.
K+7	1-Npeak	ni	If Npeak ≠ 0, then sequentially in the row you need to write the peak numbers (from the merged spectra) for which you want to output the spectra in the files F_RES\InpName.Gxx.

*If parameter choice is on DEFault, then it is necessary to specify symbol /. All parameters, that have to be specified in raw next to chosen as on default parameter, also will be specified as on DEFault.

To facilitate work with FILTER-8, we give an example of an input task file called inpfile.