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Update b_c values for Li, Pr, Nd, Sm, Eu and Yb plus isotopes (Gehlhaar 2025 and 2026) #123

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Merged
pkienzle merged 4 commits into from
Feb 27, 2026
Merged

Update b_c values for Li, Pr, Nd, Sm, Eu and Yb plus isotopes (Gehlhaar 2025 and 2026) #123

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36d23b6
Use b_c values from Gehlhaar 2026
Feb 25, 2026
4a7d849
Merge branch 'master' into update-Li
pkienzle Feb 26, 2026
ad85f93
Update change log
Feb 26, 2026
8b8124d
partially consolidate nsf changelog
Feb 26, 2026
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8 changes: 5 additions & 3 deletions ChangeLog.rst
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Expand Up @@ -23,13 +23,15 @@ Known issues
Change history
==============

2026-02-13 R2.0.3
2026-02-xx R2.0.3
-----------------

Modified:

* Update b_c bp bm and incoherent attributes for C-13
* Update nuclear_spin for Se-77 Hf-177 W-182
* Update b_c bp bm and incoherent attributes for 13C
* Update b_c for Li 6Li 7Li 141Pr Nd 142-146,148,150Nd 144,147-150,152,154Sm 153Eu 174Yb
* Update nuclear_spin for 77Se 177Hf 182W
* Generate html table of scattering lengths and cross sections
* Add comparison tables checking b_c and σ_i against b+ and b-
* Add type hinting to many of the functions

Expand Down
143 changes: 87 additions & 56 deletions periodictable/nsf.py
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Expand Up @@ -90,36 +90,59 @@
the values measured for the corresponding cross section. The comparison table
functions highlight these differences.

Tables from Sears\ [#Sears1992]_\ [#Sears2006]_, Rauch\ [#Rauch2003]_ and
Dawidowski\ [#Dawidowski2013]_ make different choices for the recommended
Tables from Sears (1992)\ [#Sears1992]_\ [#Sears2006]_, Rauch (2003)\ [#Rauch2003]_ and
Dawidowski (2013)\ [#Dawidowski2013]_ make different choices for the recommended
values. These are noted in periodictable issue #59
`<https://github.com/python-periodictable/periodictable/issues/59>`_
with changes from Sears to Rauch
`(a) <https://github.com/python-periodictable/periodictable/issues/59#issuecomment-1693686953>`__
and from Rauch to Dawidowski
`(b) <https://github.com/python-periodictable/periodictable/issues/59#issuecomment-1690212205>`__.
Mughabghab (2018)\ [#Mughabghab2018]_ provides further updates, including calculated
values for those values that have not been measured. These are not yet incorporated into the
the table.

The following newer measurements from the literature are included::

1H b_c -3.7423(12) => -3.7395(11) [1]
2H b_c 6.674(6) => 6.6681(27) [1]
4He b_c 3.26(3) => 3.0982(21) [3] (see also [5], which gives 3.075(6))
4He coherent = total cross sections computed from 4 pi b_c^2/100
natHe computed from isotopic weighting of 3He and 4He
natC b_c 6.6484(13) => 6.6472(9) [1]
natHe b_c 3.26(3) => 3.0985(21) [3] computed from 3He and 4He
6Li b_c 2.0(1) => 2.27(2) [8]
7Li b_c -2.22(2) => -2.28(2) [8]
natLi b_c -1.90(3) => -1.93(2) [8]
12C b_c 6.6535(13) => 6.6472(9) [1]
13C b_c 6.19(9) => 6.542(3); bp 5.6(5) => 6.30(14); bm 6.2(5) => 7.27(42); incoherent 0.034(11) => 0.022(20) [7]
natO b_c 5.805(4) => 5.8037(29) [1]
16O b_c 5.805(4) => 5.8037(29) [1]
17O b_c 5.6(5) => 5.867(4) [2]
18O b_c 5.84(7) => 6.009(5) [2]
natSn b_c 6.225(2) => 6.2239(13) [1]
154Sm b_c 8.0(1.0) => 8.97(6) [4]
153Eu b_c 8.22(12) => 8.85(3) [4]
119Sn b_c 6.225(2) => 6.2239(13) [1]
70Zn b_c 6.9(1.0) => 6.0(1.0) [OCR misidentified the the number]
141Pr b_c 4.58(5) => 4.44(4) [9]
natNd b_c 7.69(5) => 7.87(11) [9]
142Nd b_c 7.7(3) => 7.24(4) [9]
143Nd b_c 14.0(2.0) => 17.51(6) [9]
144Nd b_c 2.8(3) => 3.06(7) [9]
145Nd b_c 14.0(2.0) => 10.40(12) [9]
146Nd b_c 8.7(2) => 8.56(9) [9]
148Nd b_c 5.7(3) => 4.44(13) [9]
150Nd b_c 5.28(20) => 6.87(5) [9]
144Sm b_c -3.0(4.0) => 4.63(4) [11] calculated
147Sm b_c 14.0(3.0) => 6.68(5) [9]
148Sm b_c -3.0(4.0) => 6.67(7) [9]
149Sm b_c 18.7(28) => 17.84(28) [11]
150Sm b_c 14.0(3.0) => 10.05(10) [9]
152Sm b_c -5.0(6) =? -6.14(12) [9]
154Sm b_c 8.0(1.0) => 8.97(6) [4] => 9.34(9) [9]
151Eu b_c => 6.92(15) [from 94Mug1; value was missing from ATI table]
153Eu b_c 8.22(12) => 8.85(3) [4] => 8.33(11) [9]
174Yb b_c 19.2(1) => 22.02(7) [9]
191Ir b_c => 12.1(9) [6]
193Ir b_c => 9.71(18) [6]
natPb b_c 9.401(2) => 9.4024(13) [1]
natBi b_c 8.532(2) => 8.5242(18) [1]
207Pb b_c 9.401(2) => 9.4024(13) [1]
209Bi b_c 8.532(2) => 8.5242(18) [1]

He total 1.34(2) => 1.188(5) [5] (ignored; using 4 pi b_c^2/100)
He coh, total 1.34(2) => 1.188(5) [5] => 1.2065(16) [3] (using 4 pi b_c^2/100)
Ar total 0.683(4) => 0.683(5) [5] (ignored; existing value is more precise)
Kr total 7.68(13) => 7.685(26) [5]
Xe total --- => 4.344(17) [5]
Expand All @@ -131,6 +154,22 @@
[5] Haddock (2019) 10.1103/PhysRevC.100.064002
[6] Hannon (2018) 10.1107/S1600576718006064
[7] Fischer (2008) 10.1088/0953-8984/20/04/045221
[8] Gehlhaar (2025) 10.1088/1361-648X/add3a6
[9] Gehlhaar (2026) 10.1088/1361-648X/ae1ec0
[10] Mughabghab (2018) 10.1016/C2015-0-00522-6 [Z=1-60]
[11] Mughabghab (2018) 10.1016/C2015-0-00524-X [Z=61-102]

Use energy dependent b_c and σ_a from\ [#Lynn1990]_. The values at the standard
wavelength do not match the recommended values for that wavelength from other sources.
The following elements and isotopes are affected::

natSm 149Sm
natEu 151Eu
natGd 155Gd 157Gd
164Dy
natEr 167Er
natYb 168Yb 174Yb
natLu 176Lu

Other measurements since 2000 (incomplete list)::

Expand All @@ -156,23 +195,18 @@
Huffman (2004) 0.1103/PhysRevC.70.014004
3He bc' = 5.853(7)

Gehlhaar (2025) 10.1088/1361-648X/add3a6
Li bc, various isotopes

Gehlhaar (2026) 10.1088/1361-648X/ae1ec0
bc for Pr, Nd, Sm, Eu, Yb, including various isotopes
Kohlmann (2016) Zeitschrift fuer Kristallographie-Crystalline Materials 231.9 (2016): 517-523.
154Sm b_c = 8.97(6)

Von Dreele (2024) 10.1107/S1600576724005375
A fit to the Lynn and Seeger fitted resonance curves for the rare earths
using a simpler model. Also provides parameters for 103Rh, 113Cd, and 239,240Pu


The Atlas of Neutron Resonances gives evaluated values for
some of the entries missing from the table of measurements.

Mughabghab (2018)
Z=1-60: 10.1016/C2015-0-00522-6
Z=61-102: 10.1016/C2015-0-00524-X
Gehlhaar (2026) 10.1088/1361-648X/ae1ec0
170Yb b_c = 4.83(3) ignored: they note their value is not yet recommendable
because of uncertainty in b_c for other isotopes in their sample.
natSm b_c = 5.29(5) ignored: it was measured at 330.3(9) meV not 25.3 meV
natEu b_c = 5.84(5) ignored: it was measured at 168.10(5) meV not 25.3 meV

.. [#Rauch2003] Rauch, H. and Waschkowski, W. (2003)
Neutron Scattering Lengths in ILL
Expand Down Expand Up @@ -215,11 +249,17 @@
J. Appl. Cryst. 44, 618-624. doi:10.1107/S0021889811008223

.. [#Dawidowski2013] Dawidowski, J., Granada, J. R., Santisteban,
J. R., Cantargi, F., & Palomino, L. A. R. (2013).
J. R., Cantargi, F., & Palomino, L. A. R. (2013)
Appendix—Neutron Scattering Lengths and Cross Sections.
In F. Fernandez-Alonso & D. L. Price (Eds.),
Experimental Methods in the Physical Sciences (Vol. 44, pp. 471–528).
Academic Press. doi:10.1016/B978-0-12-398374-9.09989-7

.. [#Mughabghab2018] Mughabghab (2018)
Atlas of Neutron Resonances (Sixth Edition). Elsevier.
Vol I (Z=1-60) 10.1016/C2015-0-00522-6
Vol II (Z=61-102) 10.1016/C2015-0-00524-X

"""

#.. [#Koester1991] Koester, L., Rauch, H., Seymann. E. (1991)
Expand Down Expand Up @@ -1391,16 +1431,7 @@ def sld_re(atom) -> float:
# Numbers followed by '*' are estimated.
# Numbers may be given as limit, e.g., <1.0e-6
#
# [Paul Kienzle]
# * Fix typos such as 70Zn b_c 6.9(1.0) => 6.0(1.0).
# * Update bound coherent scattering length for H-1, H-2, He-4, C-12,
# O-16, O-17, O-18, Sn-119, Sm-154, Eu-153, Pb-207, Bi-209
# * Update b_c, bp, bm for C-13 and compute incoherent from bp and bm
# * Update total cross section for He, Kr, Xe
# * Usd 63-Eu-151 b_c from 84Mug1. This change is moot since this isotope
# has energy dependent isotope coeffs.
# * Use calculated values for 4He coh and total, and natHe b_c, coh and total.
# * Update Se-77 to spin -1/2; Hf-177 to spin -7/2; W-182 to spin 0
# Changes to the table are listed in the docstring at the top of the file.

# TODO: check isotope spin; some of them were wrong.
# TODO: add missing b+, b- to table using b_i values from Sears table
Expand Down Expand Up @@ -1435,9 +1466,9 @@ def sld_re(atom) -> float:
2-He,,,3.0985(21),,,,1.2065(16),0,1.2065(16),0.00747(1)
2-He-3,0.013,1/2,5.74(7),4.7(5),8.8(1.4),E,4.42(10),1.6(4),6.0(4),5333.0(7.0)
2-He-4,99.987,0,3.0982(21),,,,1.2062(16),0,1.2062(16),0
3-Li,,,-1.90(3),,,,0.454(10),0.92(3),1.37(3),70.5(3)
3-Li-6,7.5,1,2.0(1),0.67(14),4.67(17),+/-,0.51(5),0.46(5),0.97(7),940.0(4.0)
3-Li-7,92.5,3/2,-2.22(2),-4.15(6),1.00(8),+/-,0.619(11),0.78(3),1.40(3),0.0454(3)
3-Li,,,-1.93(2),,,,0.454(10),0.92(3),1.37(3),70.5(3)
3-Li-6,7.5,1,2.27(2),0.67(14),4.67(17),+/-,0.51(5),0.46(5),0.97(7),940.0(4.0)
3-Li-7,92.5,3/2,-2.28(4),-4.15(6),1.00(8),+/-,0.619(11),0.78(3),1.40(3),0.0454(3)
4-Be-9,100,3/2,7.79(1),,,,7.63(2),0.0018(9),7.63(2),0.0076(8)
5-B,,,5.30(4),,,,3.54(5),1.70(12),5.24(11),767.0(8.0)
5-B-10,19.4,3,-0.2(4),-4.2(4),5.2(4),,0.144(6),3.0(4),3.1(4),3835.0(9.0)
Expand Down Expand Up @@ -1662,27 +1693,27 @@ def sld_re(atom) -> float:
58-Ce-138,0.26,0,6.65(9),,,,5.64(15),0,5.64(15),1.1(3)
58-Ce-140,88.48,0,4.81(9),,,,2.94(11),0,2.94(11),0.57(4)
58-Ce-142,11.07,0,4.72(9),,,,2.84(11),0,2.84(11),0.95(5)
59-Pr-141,100,5/2,4.58(5),,,+/-,2.64(6),0.015(3),2.66(6),11.5(3)
60-Nd,,,7.69(5),,,,7.43(19),9.2(8),16.6(8),50.5(1.2)
60-Nd-142,27.11,0,7.7(3),,,,7.5(6),0,7.5(6),18.7(7)
60-Nd-143,12.17,7/2,14.0(2.0)*,,,,25.0(7.0),55.0(7.0),80.0(2.0),337.0(10.0)
60-Nd-144,23.85,0,2.8(3),,,,1.0(2),0,1.0(2),3.6(3)
60-Nd-145,8.5,7/2,14.0(2.0)*,,,,25.0(7.0),5.0(5.0)*,30.0(9.0),42.0(2.0)
60-Nd-146,17.22,0,8.7(2),,,,9.5(4),0,9.5(4),1.4(1)
60-Nd-148,5.7,0,5.7(3),,,,4.1(4),0,4.1(4),2.5(2)
60-Nd-150,5.6,0,5.28(20),,,,3.5(3),0,3.5(3),1.2(2)
59-Pr-141,100,5/2,4.44(4),,,+/-,2.64(6),0.015(3),2.66(6),11.5(3)
60-Nd,,,7.87(11),,,,7.43(19),9.2(8),16.6(8),50.5(1.2)
60-Nd-142,27.11,0,7.24(4),,,,7.5(6),0,7.5(6),18.7(7)
60-Nd-143,12.17,7/2,17.51(6)*,,,,25.0(7.0),55.0(7.0),80.0(2.0),337.0(10.0)
60-Nd-144,23.85,0,3.06(7),,,,1.0(2),0,1.0(2),3.6(3)
60-Nd-145,8.5,7/2,10.40(12)*,,,,25.0(7.0),5.0(5.0)*,30.0(9.0),42.0(2.0)
60-Nd-146,17.22,0,8.56(9),,,,9.5(4),0,9.5(4),1.4(1)
60-Nd-148,5.7,0,4.44(13),,,,4.1(4),0,4.1(4),2.5(2)
60-Nd-150,5.6,0,6.87(5),,,,3.5(3),0,3.5(3),1.2(2)
61-Pm-147,2.62 Y,7/2,12.6(4),,,,20.0(1.3),1.3(2.0),21.3(1.5),168.4(3.5)
62-Sm,,,0.00(5),,,E,0.422(9),39.0(3.0),39.4(3.0),5922.0(56.0)
62-Sm-144,3.1,0,-3.0(4.0)*,,,,1.0(3.0),0,1.0(3.0),0.7(3)
62-Sm-147,15,7/2,14.0(3.0),,,,25.0(11.0),14.0(19.0),39.0(16.0),57.0(3.0)
62-Sm-148,11.2,0,-3.0(4.0)*,,,,1.0(3.0),0,1.0(3.0),2.4(6)
62-Sm-149,13.8,7/2,18.7(28),,,E,63.5(6),137.0(5.0),200.0(5.0),42080.0(400.0)
62-Sm-150,7.4,0,14.0(3.0),,,,25.0(11.0),0,25.0(11.0),104.0(4.0)
62-Sm-152,26.7,0,-5.0(6),,,,3.1(8),0,3.1(8),206.0(6.0)
62-Sm-154,22.8,0,8.97(6),,,,11.0(2.0),0,11.0(2.0),8.4(5)
62-Sm-144,3.1,0,4.63(4)*,,,,1.0(3.0),0,1.0(3.0),0.7(3)
62-Sm-147,15,7/2,6.68(5),,,,25.0(11.0),14.0(19.0),39.0(16.0),57.0(3.0)
62-Sm-148,11.2,0,6.67(7)*,,,,1.0(3.0),0,1.0(3.0),2.4(6)
62-Sm-149,13.8,7/2,17.84(28),,,E,63.5(6),137.0(5.0),200.0(5.0),42080.0(400.0)
62-Sm-150,7.4,0,10.05(10),,,,25.0(11.0),0,25.0(11.0),104.0(4.0)
62-Sm-152,26.7,0,-6.14(12),,,,3.1(8),0,3.1(8),206.0(6.0)
62-Sm-154,22.8,0,9.34(9),,,,11.0(2.0),0,11.0(2.0),8.4(5)
63-Eu,,,5.3(3),,,E,6.57(4),2.5(4),9.2(4),4530.0(40.0)
63-Eu-151,47.8,5/2,6.92(15),,,E,5.5(2),3.1(4),8.6(4),9100.0(100.0)
63-Eu-153,52.8,5/2,8.85(3),,,,8.5(2),1.3(7),9.8(7),312.0(7.0)
63-Eu-153,52.8,5/2,8.33(11),,,,8.5(2),1.3(7),9.8(7),312.0(7.0)
64-Gd,,,9.5(2),,,E,29.3(8),151.0(2.0),180.0(2.0),49700.0(125.0)
64-Gd-152,0.2,0,10.0(3.0)*,,,,13.0(8.0),0,13.0(8.0),735.0(20.0)
64-Gd-154,2.2,0,10.0(3.0)*,,,,13.0(8.0),0,13.0(8.0),85.0(12.0)
Expand Down Expand Up @@ -1715,7 +1746,7 @@ def sld_re(atom) -> float:
70-Yb-171,14.3,1/2,9.7(1),6.5(2),19.4(4),,11.7(2),3.9(2),15.6(3),48.6(2.5)
70-Yb-172,21.9,0,9.5(1),,,,11.2(2),0,11.2(2),0.8(4)
70-Yb-173,16.3,5/2,9.56(10),2.5(2),13.3(3),,11.5(2),3.5,15,17.1(1.3)
70-Yb-174,31.8,0,19.2(1),,,,46.8(5),0,46.8(5),69.4(5.0)
70-Yb-174,31.8,0,22.02(7),,,,46.8(5),0,46.8(5),69.4(5.0)
70-Yb-176,12.7,0,8.7(1),,,,9.6(2),0,9.6(2),2.85(5)
71-Lu,,,7.21(3),,,,6.53(5),0.7(4),7.2(4),74.0(2.0)
71-Lu-175,97.4,7/2,7.28(9),,,,6.59(5),0.6(4),7.2(4),21.0(3.0)
Expand Down