Summary of simulation results at the NEAR Station (February 2021)

Design example of collimator (from M Barbagallo's presentation)

NEAR station scoring positions (from M Barbagallo's presentation)

NOTE ID from 81 to 86 are for scoring position 27, 91 to 96 are for scoring position 30.

Filters

Filter material in all cases :	Boron enriched (95% B-10 and 5% B-11)
Density :	2.46 g/cm3 (0.137 atoms/b for 1.0 cm thickness)
Filter thickness grid [cm] :	0.0   0.1   0.2   0.3   0.4   0.5   0.6   0.7   0.8   0.9   1.0   1.1   1.2   1.3   1.4   1.5   2.0   2.5   3.0   3.5   4.0   4.5   5.0

M81: No-moderator

no moderator

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M81	30	-	27	0.39641E+09	Boron (enriched)	1.0	0.23005E+09	No-moderator	M81-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

Systematics of M-SACS/NS-SACS

M82: Shelf-position-light

moderator on the shelf, 25 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M82	30	AlF3	27	0.13209E+09	Boron (enriched)	1.0	0.67803E+08	Shelf-position-light	M82-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

Systematics of M-SACS/NS-SACS

M83: Shelf-position-heavy

moderator on the shelf, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M83	30	AlF3	27	0.92037E+08	Boron (enriched)	1.0	0.42348E+08	Shelf-position-heavy	M83-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

Systematics of M-SACS/NS-SACS

M84: Al-moderator

pure Aluminum moderator, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M84	30	Al	27	0.12942E+09	Boron (enriched)	1.0	0.65966E+08	Al-moderator	M84-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

Systematics of M-SACS/NS-SACS

M85: AlF3+BPE-moderator

AlF3(10cm) + BPE(10cm) moderator, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M85	30	AlF3+BPE	27	0.52383E+08	Boron (enriched)	1.0	0.24307E+08	AlF3+BPE-moderator	M85-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

Systematics of M-SACS/NS-SACS

M86: Al+BPE-moderator

Al(10cm) + BPE(10cm) moderator, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M86	30	Al+BPE	27	0.53485E+08	Boron (enriched)	1.0	0.25987E+08	Al+BPE-moderator	M86-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

Systematics of M-SACS/NS-SACS

M91: No-moderator

no moderator

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M91	30	-	30	0.55493E+11	Boron (enriched)	1.0	0.22471E+11	No-moderator	M91-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

M92: Shelf-position-light

moderator on the shelf, 25 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M92	30	AlF3	30	0.42160E+11	Boron (enriched)	1.0	0.15011E+11	Shelf-position-light	M92-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

M93: Shelf-position-heavy

moderator on the shelf, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M93	30	AlF3	30	0.38898E+11	Boron (enriched)	1.0	0.13204E+11	Shelf-position-heavy	M93-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

M94: Al-moderator

pure Aluminum moderator, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M94	30	Al	30	0.41498E+11	Boron (enriched)	1.0	0.14831E+11	Al-moderator	M94-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

M95: AlF3+BPE-moderator

AlF3(10cm) + BPE(10cm) moderator, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M95	30	AlF3+BPE	30	0.33209E+11	Boron (enriched)	1.0	0.11071E+11	AlF3+BPE-moderator	M95-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

M96: Al+BPE-moderator

Al(10cm) + BPE(10cm) moderator, 40 kg

ID	BPE thickness [cm]	moderator	scoring position	flux [n/cm2/pp]	filter type	filter thickness [cm]	filtered flux [n/cm2/pp]	full numerical printout	input nspectrum file
M96	30	Al+BPE	30	0.33646E+11	Boron (enriched)	1.0	0.11356E+11	Al+BPE-moderator	M96-input-nspectrum

Neutron flux for plain and filtered (1 cm thickness) beams

Comparison to a maxwellian spectrum and cumulative SACS

Movie frames for different the filter thickness grid

Fit goodness

A quantitave comparison between the filtered spectrum and a pure maxwelling spectrum can be provided by the overlap betwwn the two curves. The maxwellian spectrum area is usually smaller th an the filtered spectrum. In the figure below, the overlap is shown as a function of the filter thickness for all the configurations considered here.

Integrated Flux (unfiltered)

ID	setup	Total [n/cm2/pp]	E < 1 keV	1 keV < E < 1 MeV	E > 1 MeV
M81	No-moderator	3.9641e+08	1.9301e+07	2.4557e+08	1.3154e+08
M82	Shelf-position-light	1.3209e+08	1.5372e+07	7.5527e+07	4.1196e+07
M83	Shelf-position-heavy	9.2037e+07	1.4823e+07	5.2430e+07	2.4785e+07
M84	Al-moderator	1.2942e+08	1.5303e+07	7.8492e+07	3.5620e+07
M85	AlF3+BPE-moderator	5.2383e+07	1.1219e+07	2.3923e+07	1.7241e+07
M86	Al+BPE-moderator	5.3485e+07	1.1024e+07	2.2937e+07	1.9524e+07
M91	No-moderator	5.5493e+10	1.0668e+10	3.9751e+10	5.0741e+09
M92	Shelf-position-light	4.2160e+10	1.0467e+10	2.8952e+10	2.7411e+09
M93	Shelf-position-heavy	3.8898e+10	1.0394e+10	2.6325e+10	2.1788e+09
M94	Al-moderator	4.1498e+10	1.0316e+10	2.8619e+10	2.5626e+09
M95	AlF3+BPE-moderator	3.3209e+10	9.4801e+09	2.1899e+10	1.8291e+09
M96	Al+BPE-moderator	3.3646e+10	9.4573e+09	2.2271e+10	1.9183e+09

-- AlbertoMengoni - 2021-02-19