templ_enum.cif: explicitly provide the data source for data in the length_neutron save frame

[vaitkus]

The length_neutron save frame seemingly contains the bound coherent neutron scattering lengths of elements. However, it is not clear where this data were originally taken from. I have compared it with data from Table 4.4.4.1 in ITC Vol. C (2004) and there are some significant differences:

• Values for 26 elements differ (e.g. Mo: 6.95 vs 6.715).
• Some values in the ITC are given as complex numbers while in templ_enum.cif all values are given as real numbers (e.g. values for Sm are given as "0.80(2) - 1.65(2)i" and "4.2" respectively).
• Some values which are left unspecified in ITC are given as 0 in templ_enum.cif (e.g. for Po, At, Rn, Fr).
• Some values are only given in templ_enum.cif (e.g. for Bk and Cf).

Since these values are (probably) intended to be used as defaults, it is quite important to track down the data source and explicitly record it in the temp_enum.cif file. This could be done by adding the _description.text attribute or introducing a new attribute altogether (e.g. _description.data_source).

[rowlesmr]

Also, scattering lengths are isotope-specific.

Can/should we give a listing for all isotopes? Can we even denote isotopes in the current atom symbol notation?

.

For completeness, these are the values that TOPAS uses:
(the link is dead. Wayback has a copy: https://web.archive.org/web/20060924043313/http://www.ccp14.ac.uk/ccp/web-mirrors/neutrons/n-scatter/n-lengths/LIST~1.HTM)

/*
Scattering lengths from:																		
http://www.ccp14.ac.uk/ccp/web-mirrors/neutrons/n-scatter/n-lengths/LIST~1.HTM
*/

neutron {
   H  -0.3739
   1H  -0.37406
   2H  0.6671 D 0.6671
   3H  0.4792
   He  0.326
   3He  0.574
   4He  0.326
   Li  -0.19
   6Li  0.2
   7Li  -0.222
   Be  0.779
   B  0.53
   10B  -0.01
   11B  0.665
   C  0.6646
   12C  0.66511
   13C  0.619
   N  0.936
   14N  0.937
   15N  0.644
   O  0.5803
   16O  0.5803
   17O  0.578
   18O  0.584
   F  0.5654
   Ne  0.4566
   20Ne  0.4631
   21Ne  0.666
   22Ne  0.387
   Na  0.363
   Mg  0.5375
   24Mg  0.566
   25Mg  0.362
   26Mg  0.489
   Al  0.3449
   Si  0.41491
   28Si  0.4107
   29Si  0.47
   30Si  0.458
   P  0.513
   S  0.2847
   32S  0.2804
   33S  0.474
   34S  0.348
   36S  0.3
   Cl  0.9577 
   35Cl  1.165
   37Cl  0.308
   Ar  0.1909
   36Ar  2.49
   38Ar  0.35
   40Ar  0.183
   K  0.367
   39K  0.374
   40K  0.3
   41K  0.269
   Ca  0.47
   40Ca  0.48
   42Ca  0.336
   43Ca  -0.156
   44Ca  0.142
   46Ca  0.36
   48Ca  0.039
   Sc  1.229
   Ti  -0.3438
   46Ti  0.493
   47Ti  0.363
   48Ti  -0.608
   49Ti  0.104
   50Ti  0.618
   V  -0.03824
   50V  0.76
   51V  -0.0402
   Cr  0.3635
   50Cr  -0.45
   52Cr  0.492
   53Cr  -0.42
   54Cr  0.455
   Mn  -0.373
   Fe  0.945
   54Fe  0.42
   56Fe  0.994
   57Fe  0.23
   58Fe  1.5
   Co  0.249
   Ni  1.03
   58Ni  1.44
   60Ni  0.28
   61Ni  0.76
   62Ni  -0.87
   64Ni  -0.037
   Cu  0.7718
   63Cu  0.643
   65Cu  1.061
   Zn  0.568
   64Zn  0.522
   66Zn  0.597
   67Zn  0.756
   68Zn  0.603
   70Zn  0.6
   Ga  0.7288
   69Ga  0.788
   71Ga  0.64
   Ge  0.8185
   70Ge  1
   72Ge  0.851
   73Ge  0.502
   74Ge  0.758
   76Ge  0.82
   As  0.658
   Se  0.797
   74Se  0.08
   76Se  1.22
   77Se  0.825
   78Se  0.824
   80Se  0.748
   82Se  0.634
   Br  0.6795
   79Br  0.68
   81Br  0.679
   Kr  0.781
   86Kr  0.81
   Rb  0.709
   85Rb  0.703
   87Rb  0.723
   Sr  0.702
   84Sr  0.7
   86Sr  0.567
   87Sr  0.74
   88Sr  0.715
   Y  0.775
   Zr  0.716
   90Zr  0.64
   91Zr  0.87
   92Zr  0.74
   94Zr  0.82
   96Zr  0.55
   Nb  0.7054
   Mo  0.6715
   92Mo  0.691
   94Mo  0.68
   95Mo  0.691
   96Mo  0.62
   97Mo  0.724
   98Mo  0.658
   100Mo  0.673
   Tc  0.68
   Ru  0.703
   Rh  0.588
   Pd  0.591
   102Pd  0.77
   104Pd  0.77
   105Pd  0.55
   106Pd  0.64
   108Pd  0.41
   110Pd  0.77
   Ag  0.5922
   107Ag  0.7555
   109Ag  0.4165
   Cd  0.487
   106Cd  0.5
   108Cd  0.54
   110Cd  0.59
   111Cd  0.65
   112Cd  0.64
   113Cd  -0.8
   114Cd  0.75
   116Cd  0.63
   In  0.4065
   113In  0.539
   115In  0.401
   Sn  0.6225
   112Sn  0.6
   114Sn  0.62
   115Sn  0.6
   116Sn  0.593
   117Sn  0.648
   118Sn  0.607
   119Sn  0.612
   120Sn  0.649
   122Sn  0.574
   124Sn  0.597
   Sb  0.557
   121Sb  0.571
   123Sb  0.538
   Te  0.58
   120Te  0.53
   122Te  0.38
   123Te  -0.005
   124Te  0.796
   125Te  0.502
   126Te  0.556
   128Te  0.589
   130Te  0.602
   I  0.528
   Xe  0.492
   Cs  0.542
   Ba  0.507
   130Ba  -0.36
   132Ba  0.78
   134Ba  0.57
   135Ba  0.467
   136Ba  0.491
   137Ba  0.683
   138Ba  0.484
   La  0.824
   138La  0.8
   139La  0.824
   Ce  0.484
   136Ce  0.58
   138Ce  0.67
   140Ce  0.484
   142Ce  0.475
   Pr  0.458
   Nd  0.769
   142Nd  0.77
   143Nd  1.4
   144Nd  0.28
   145Nd  1.4
   146Nd  0.87
   148Nd  0.57
   150Nd  0.53
   Pm  1.26
   Sm  0.08
   144Sm  -0.3
   147Sm  1.4
   148Sm  -0.3
   149Sm  -1.92
   150Sm  1.4
   152Sm  -0.5
   154Sm  0.93
   Eu  0.722
   151Eu  0.613
   153Eu  0.822
   Gd  0.65
   152Gd  1
   154Gd  1
   155Gd  0.6
   156Gd  0.63
   157Gd  -0.114
   158Gd  0.9
   160Gd  0.915
   Tb  0.738
   Dy  1.69
   156Dy  0.61
   158Dy  0.6
   160Dy  0.67
   161Dy  1.03
   162Dy  -0.14
   163Dy  0.5
   164Dy  4.94
   Ho  0.801
   Er  0.779
   162Er  0.88
   164Er  0.82
   166Er  1.06
   167Er  0.3
   168Er  0.74
   170Er  0.96
   Tm  0.707
   Yb  1.243
   168Yb  -0.407
   170Yb  0.677
   171Yb  0.966
   172Yb  0.943
   173Yb  0.956
   174Yb  1.93
   176Yb  0.872
   Lu  0.721
   175Lu  0.724
   176Lu  0.61
   Hf  0.77
   174Hf  1.09
   176Hf  0.661
   177Hf  0.08
   178Hf  0.59
   179Hf  0.746
   180Hf  1.32
   Ta  0.691
   180Ta  0.7
   181Ta  0.691
   W  0.486
   180W  0.5
   182W  0.697
   183W  0.653
   184W  0.748
   186W  -0.072
   Re  0.92
   185Re  0.9
   187Re  0.93
   Os  1.07
   186Os  1.16
   187Os  1
   188Os  0.76
   189Os  1.07
   190Os  1.1
   192Os  1.15
   Ir  1.06
   Pt  0.96
   190Pt  0.9
   192Pt  0.99
   194Pt  1.055
   195Pt  0.883
   196Pt  0.989
   198Pt  0.78
   Au  0.763
   Hg  1.2692
   196Hg  3.03
   199Hg  1.69
   Tl  0.8776
   203Tl  0.699
   205Tl  0.952
   Pb  0.9405
   204Pb  0.99
   206Pb  0.922
   207Pb  0.928
   208Pb  0.95
   Bi  0.8532
   Ra  1
   Th  1.031
   Pa  0.91
   U  0.8417
   233U  1.01
   234U  1.24
   235U  1.047
   238U  0.8402
   Np  1.055
   238Pu  1.41
   239Pu  0.77
   240Pu  0.35
   242Pu  0.81
   Am  0.83
   244Cm  0.95
   246Cm  0.93
   248Cm  0.77
}

[jamesrhester]

I will see if I can find the original source of these numbers. Note that the neutron scattering length table is not actually used by the main dictionary (yet).

[vaitkus]

Thank you. In case the data for other save frames was also provided in the same place, it would also be useful to get the references for the atomic radii and mass values.

[jamesrhester]

The values in the tables agree with my 1992 ITVC edition, table 4.4.4.1. Well, at least the Mo discrepancy noted above by @vaitkus doesn't exist. The remaining issues are still present, of course. So I think we can conclude that 1992 ITVC table 4.4.4.1 is the source, plus some other source for Bk. My neutron "blue book" doesn't even have Bk.

We should obviously update the tables to properly include imaginary parts and isotopes from the latest IT tabulation.