Component Manual for the Neutron Ray-Tracing Package McStas, version 3.8.6

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1.4  About data files

Some components require external data files, e.g. lattice crystallographic definitions for Laue and powder pattern diffraction, \(S(q,\omega )\) tables for inelastic scattering, neutron events files for virtual sources, transmission and reflectivity files, etc.

Such files distributed with McStas are located in the data sub-directory of the McStas library. Components that make use of the McStas file system, including the read-table library (see section B.2) may access all McStas data files without making local copies. Of course, you are welcome to define your own data files, and eventually contribute to McStas if you find them useful.

File extensions are not compulsory but help in identifying relevant files per application. We list powder and liquid data files from the McStas library in Tables 1.2 and 1.3. These files contain an extensive header describing physical properties with references, and are specially suited for the PowderN (see 9.3) and Isotropic_Sqw components (see 9.7). Whenever using any \(S(q,\omega )\) data for the Isotropic_Sqw component, we kindly request to cite the corresponding reference.

MCSTAS/data

Description

*.lau

Laue pattern file, as issued from Crystallographica. For use with Single_crystal, PowderN, and Isotropic_Sqw. Data: [ h k l Mult. d-space 2Theta F-squared ]

*.laz

Powder pattern file, as obtained from Lazy/ICSD. For use with PowderN, Isotropic_Sqw and possibly Single_crystal.

*.trm

transmission file, typically for monochromator crystals and filters. Data: [ k (Angs-1) , Transmission (0-1) ]

*.rfl

reflectivity file, typically for mirrors and monochromator crystals. Data: [ k (Angs-1) , Reflectivity (0-1) ]

*.sqw

\(S(q,\omega )\) files for Isotropic_Sqw component. Data: [q] [\(\omega \)] [\(S(q,\omega )\)]


Table 1.1.: Data files of the McStas library.

MCSTAS/data \(\sigma _{coh}\) \(\sigma _{inc}\) \(\sigma _{abs}\) \(T_m\) \(c\)

Note

File name [barns] [barns] [barns] [K] [m/s]

Ag.laz 4.407 0.58 63.3 1234.9 2600

Al2O3_sapphire.laz 15.683 0.0188 0.4625 2273

Al.laz 1.495 0.0082 0.231 933.5 5100

.lau

Au.laz 7.32 0.43 98.65 1337.4 1740

B4C.laz 19.71 6.801 3068 2718

Ba.laz 3.23 0.15 29.0 1000 1620

Be.laz 7.63 0.0018 0.0076 1560 13000

BeO.laz 11.85 0.003 0.008 2650

.lau
Bi.laz 9.148 0.0084 0.0338 544.5 1790

C60.lau 5.551 0.001 0.0035

C_diamond.laz 5.551 0.001 0.0035 4400 18350

.lau

C_graphite.laz 5.551 0.001 0.0035 3800 18350

.lau

Cd.laz 3.04 3.46 2520 594.2 2310

Cr.laz 1.660 1.83 3.05 2180 5940

Cs.laz 3.69 0.21 29.0 301.6 1090

\(c\) in liquid

Cu.laz 7.485 0.55 3.78 1357.8 3570

Fe.laz 11.22 0.4 2.56 1811 4910

Ga.laz 6.675 0.16 2.75 302.91 2740

Gd.laz 29.3 151 49700 1585 2680

Ge.laz 8.42 0.18 2.2 1211.4 5400

H2O_ice_1h.laz 7.75 160.52 0.6652 273

Hg.laz 20.24 6.6 372.3 234.32 1407

I2.laz 7.0 0.62 12.3 386.85

In.laz 2.08 0.54 193.8 429.75 1215

K.laz .69 0.27 2.1 336.53 2000

LiF.laz 4.46 0.921 70.51 1140

Li.laz 0.454 0.92 70.5 453.69 6000

Nb.laz 8.57 0.0024 1.15 2750 3480

Ni.laz 13.3 5.2 4.49 1728 4970

Pb.laz 11.115 0.003 0.171 600.61 1260

Pd.laz 4.39 0.093 6.9 1828.05 3070

Pt.laz 11.58 0.13 10.3 2041.4 2680

Rb.laz 6.32 0.5 0.38 312.46 1300

Se_alpha.laz 7.98 0.32 11.7 494 3350

Se_beta.laz 7.98 0.32 11.7 494 3350

Si.laz 2.163 0.004 0.171 1687 2200

SiO2_quartza.laz 10.625 0.0056 0.1714 846

.lau

SiO2_quartzb.laz 10.625 0.0056 0.1714 1140

.lau

Sn_alpha.laz 4.871 0.022 0.626 505.08

Sn_beta.laz 4.871 0.022 0.626 505.08 2500

Ti.laz 1.485 2.87 6.09 1941 4140

Tl.laz 9.678 0.21 3.43 577 818

V.laz .0184 4.935 5.08 2183 4560

Zn.laz 4.054 0.077 1.11 692.68 3700

Zr.laz 6.44 0.02 0.185 2128 3800


Table 1.2.: Powders of the McStas library [Ics; DL03]. Low \(c\) and high \(\sigma _{abs}\) materials are highlighted. Files are given in LAZY format, but may exist as well in Crystallographica .lau format as well.

MCSTAS/data \(\sigma _{coh}\) \(\sigma _{inc}\) \(\sigma _{abs}\) \(T_m\) \(c\)

Note

File name [barns] [barns] [barns] [K] [m/s]

Cs_liq_tot.sqw 3.69 0.21 29.0 301.6 1090

liquid cesium. Bodensteiner et al, Phys. Rev. A, 45 (1992) 5709 and 46 (1992) 3574.

D2_liq_21_tot.sqw 7.64 0 0.00052 21

liquid deuterium. Measured. Frei et al, PHYSICAL REVIEW B 80 (2009) 064301

D2_pow_21_tot.sqw 7.64 0 0.00052 12

powder deuterium. Measured. Frei et al, PHYSICAL REVIEW B 80 (2009) 064301

D2O_liq_290_coh and D_liq_290_inc 15.4 4.1 0.0012 290

liquid heavy water. Classical MD. E. Farhi et al, J. Nucl. Sci. Tech. (2015)

D2O_liq_290_tot 15.4 4.1 0.0012 290

liquid heavy water. Measured. E. Farhi et al, J. Nucl. Sci. Tech. (2015)

Ge_liq_coh.sqw and Ge_liq_inc.sqw 8.42 0.18 2.2 1211.4 5400

liquid germanium. Ab-initio MD. Hugouvieux V, Farhi E, Johnson MR, et al., PRB 75 (2007) 104208

H2O_liq_290_coh and H2O_liq_290_inc 7.75 161 0.665 290 1530

liquid water. Classical MD. E. Farhi et al, J. Nucl. Sci. Tech. (2015)

H2O_liq_290_tot 7.75 161 0.665 290 1530

liquid water. Measured. E. Farhi et al, J. Nucl. Sci. Tech. (2015)

He4_liq_coh.sqw 1.34 0 0.00747 2 240

liquid helium. Measured (constant width). R.J. Donnelly et al., J. Low Temp. Phys., 44 (1981) 471

He4_liq_1_coh.sqw 1.34 0 0.00747 1 240

liquid helium. Measured. K. Andersen et al, J Phys Cond Mat, 6 (1994) 821

Ne_liq_tot.sqw 2.62 0.008 0.039 24.56 591

liquid neon. Measured. Buyers, Sears et al, Phys Rev A 11 (1975) 697

Rb_liq_coh.sqw and Rb_liq_inc.sqw 6.32 0.5 0.38 312.46 1300

liquid rubidium. Classical MD. E. Farhi, V. Hugouvieux, M.R. Johnson, W. Kob, Journal of Computational Physics 228 (2009) 5251-5261

Rb_liq_tot.sqw 6.32 0.5 0.38 312.46 1300

liquid rubidium. Measured. J. Copley et al, PRA 9 (1974) 1656 and PRL 32 (1974) 49


Table 1.3.: Liquids of the McStas library [Ics; DL03]. Low \(c\) and high \(\sigma _{abs}\) materials are highlighted.

McStas itself generates both simulation and monitor data files, which structure is explained in the User Manual (see end of chapter ’Running McStas’).

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