Closed pkienzle closed 1 year ago
pkienzle
commented
1 year ago Note: 30-Zn-70 appears to be different because of a typo in my version of the tables. The file https://github.com/pkienzle/periodictable/blob/master/doc/nsf.pdf lists it as 6 ± 1, as does Vol C of the international tables for crystallography. I will fix this value. I would like to find references for the others prior to changing them.
pkienzle
commented
1 year ago Further checks on b_c against Sears (Int. Cryst. Tables C), Rauch (ATI table), and Dawidowski (Daw below).
1-H b_c: Sears = -3.7390(11) [??] Rauch = -3.7409(11) Daw = Sears
5-B-10 b_c: Sears = -0.1(4) Rauch = -0.2(4) [83Koe1] Daw = -0.1(3) [??]
8-0-17 b_c: Sears = 5.78(12) [68Val1] Rauch = 5.6(5) [98Ale1] Daw = 5.66(5) [81Mug1]
18-Ar-40 b_c: Sears = 1.83(5) [73Mug1] Rauch= 1.7 [62Chr1,57Hen1] Daw = 1.84(3) [81Mug1]
66-Dy-158 b_c: Sears = 6.(4.) [86Sea1] Rauch = Sears Daw = 6.7(4.0) [??]
94-Pu-238 b_c: Sears = 14.1(5) [84Mug1] Rauch = None Daw = SearsOther than 66-Dy-158 the values used by Dawidowski were available to Rauch. I have no basis for choosing one over the other so I will keep the recommended values from Rauch.
Note: my comparison program had some mislabeled columns. The "Energy dependent?" column in Rauch was replaced with a "bi" column in Dawidowski. Using the correct labels and ignoring change in uncertainty here are the remaining differences
0-n-1 tot: 43.01(2) => 44.89(4)
1-H-1 inc: 80.27(6) => 79.91(4) | tot: 82.03(6) => 81.67(4)
1-H-2 inc: 2.05(3) => 2.04(3)
2-He-3 inc: 1.6(4) => 1.38(16) | tot: 6.0(4) => 5.8(2)
14-Si-29 inc: 0.001(2) => 0.79(3) | tot: 2.78(12) => 3.57(15)
45-Rh-103 inc: 0.3(3)* => 0.047(7) | tot: 4.6(3) => 4.39(7) I looked for measurements of scattering length post-2000 and found nothing to support changing the values.
pkienzle
commented
1 year ago Changes from Sears to Rauch (>5%):
5-B-10 b_c: -0.1(3) => -0.2(4)
18-Ar-40 b_c: 1.830(6) => 1.7
22-Ti inc: 2.63(3) => 2.87(3) | tot: 4.06(3) => 4.35(3) | abs: 6.43(6) => 6.09(13)
22-Ti-46 tot: 2.80(6) => 3.05(7)
22-Ti-48 tot: 4.32(3) => 4.65(3) | abs: 8.30(9) => 7.84(25)
22-Ti-50 tot: 4.34(15) => 4.80(12)
23-V b_c: -0.3824(12) => -0.443(14)
38-Sr-84 b_c: 7.(1.) E => 5.0(2.0)
52-Te abs: 4.05(5) => 4.7(1)
62-Sm-154 b_c: 9.3(1.0) => 8.0(1.0)
67-Ho-165 b_c: 8.01(8) => 8.44(3)
81-Tl-203 b_c: 6.99(16) => 8.51(8)
81-Tl-205 b_c: 9.52(7) => 8.87(7)
82-Pb-204 b_c: 9.90(10) => 10.893(78) and for completeness, all changes from Sears to Rauch:
1-H b_c: -3.7390(11) => -3.7409(11)
1-H-1 b_c: -3.7406(11) => -3.7423(12)
1-H-2 b_c: 6.671(4) => 6.674(6)
1-H-3 abs: 0 => <6.0E-6
3-Li b_c: -1.90(2) => -1.90(3)
3-Li-6 b_c: 2.00(11) => 2.0(1) | inc: 0.46(2) => 0.46(5)
5-B-10 b_c: -0.1(3) => -0.2(4)
5-B-11 inc: 0.22(6) => 0.21(7) | tot: 5.78(9) => 5.77(10)
6-C b_c: 6.6460(12) => 6.6484(13)
6-C-12 b_c: 6.6511(16) => 6.6535(14)
6-C-13 inc: 0.034(12) => 0.034(11)
7-N-14 inc: 0.5(1) => 0.50(12)
8-O b_c: 5.803(4) => 5.805(4)
8-O-16 b_c: 5.803(4) => 5.805(5)
8-O-17 b_c: 5.78(12) => 5.6(5)
9-F-19 b_c: 5.654(10) => 5.654(12)
12-Mg-24 b_c: 5.66(3) => 5.49(18)
13-Al-27 inc: 0.0082(7) => 0.0082(6)
14-Si b_c: 4.1491(10) => 4.15071(22)
14-Si-28 b_c: 4.107(6) => 4.106(6)
17-Cl b_c: 9.5770(8) => 9.5792(8)
17-Cl-35 b_c: 11.65(2) => 11.70(9)
18-Ar inc: 0.22(2) => 0.225(5)
18-Ar-36 b_c: 24.90(7) => 24.9(7)
18-Ar-38 abs: 0.8(2) => 0.8(5)
18-Ar-40 b_c: 1.830(6) => 1.7
19-K-39 b_c: 3.74(2) => 3.79(2)
19-K-40 b_c: 3.(1.) E => 3.1(1.0)*
20-Ca-40 b_c: 4.80(2) => 4.78(5)
20-Ca-43 inc: => 0.5(5)
20-Ca-46 b_c: 3.6(2) => 3.55(21)
21-Sc-45 b_c: 12.29(11) => 12.1(1) | inc: 4.5(5) => 4.5(3)
22-Ti inc: 2.63(3) => 2.87(3) | tot: 4.06(3) => 4.35(3) | abs: 6.43(6) => 6.09(13)
22-Ti-46 b_c: 4.725(5) => 4.72(5) | tot: 2.80(6) => 3.05(7)
22-Ti-47 tot: 3.1(2) => 3.2(2)
22-Ti-48 tot: 4.32(3) => 4.65(3) | abs: 8.30(9) => 7.84(25)
22-Ti-50 tot: 4.34(15) => 4.80(12)
23-V b_c: -0.3824(12) => -0.443(14) | abs: 5.08(2) => 5.08(4)
24-Cr abs: 3.05(8) => 3.05(6)
24-Cr-52 b_c: 4.920(10) => 4.914(15)
25-Mn-55 tot: 2.17(3) => 2.15(3)
26-Fe-56 b_c: 9.94(3) => 10.1(2)
29-Cu-63 b_c: 6.43(15) => 6.477(13)
29-Cu-65 b_c: 10.61(19) => 10.204(20)
30-Zn b_c: 5.60(5) => 5.680(5)
30-Zn-64 b_c: 5.22(4) => 5.23(4)
30-Zn-66 b_c: 5.97(5) => 5.98(5)
30-Zn-67 b_c: 7.56(8) => 7.58(8)
30-Zn-68 b_c: 6.03(3) => 6.04(3)
31-Ga-69 b_c: 7.88(2) => 8.043(16)
31-Ga-71 b_c: 6.40(3) => 6.170(11)
32-Ge-76 b_c: 8.21(1.5) => 8.2(1.5)
34-Se inc: 0.33(6) => 0.32(6)
34-Se-77 inc: 0.05(26) => 0.05(25)
35-Br b_c: 6.795(15) => 6.79(2)
35-Br-79 b_c: 6.80(7) => 6.79(7)
35-Br-81 b_c: 6.79(7) => 6.78(7)
36-Kr-83 abs: => 185.0(30.0)
36-Kr-84 tot: => 6.6
36-Kr-86 b_c: 8.1(2) => 8.07(26)
37-Rb b_c: 7.09(2) => 7.08(2) | abs: 0.38(4) => 0.38(1)
37-Rb-85 b_c: 7.03(10) => 7.07(10) | inc: E => 0.5(5)*
37-Rb-87 b_c: 7.23(12) => 7.27(12) | inc: E => 0.5(5)*
38-Sr-84 b_c: 7.(1.) E => 5.0(2.0)
38-Sr-86 b_c: 5.67(5) => 5.68(5)
38-Sr-87 b_c: 7.40(7) => 7.41(7) | inc: E => 0.5(5)*
38-Sr-88 b_c: 7.15(6) => 7.16(6)
40-Zr-90 b_c: 6.4(1) => 6.5(1)
40-Zr-91 b_c: 8.7(1) => 8.8(1)
40-Zr-92 b_c: 7.4(2) => 7.5(2)
40-Zr-94 b_c: 8.2(2) => 8.3(2)
41-Nb-93 abs: 1.15(5) => 1.15(6)
42-Mo b_c: 6.715(2) => 6.715(20)
42-Mo-92 b_c: 6.91(8) => 6.93(8)
42-Mo-94 b_c: 6.80(7) => 6.82(7)
42-Mo-95 b_c: 6.91(6) => 6.93(7) | inc: E => 0.5(5)*
42-Mo-96 b_c: 6.20(6) => 6.22(6)
42-Mo-97 b_c: 7.24(8) => 7.26(8) | inc: E => 0.5(5)*
42-Mo-98 b_c: 6.58(7) => 6.60(7)
42-Mo-100 b_c: 6.73(7) => 6.75(7)
43-Tc-99 inc: E => 0.5(5)*
44-Ru b_c: 7.03(3) => 7.02(2)
44-Ru-96 b_c: 0 => | inc: => 0 | abs: => 0.28(2)
44-Ru-98 b_c: 0 => | inc: => 0 | abs: => <8.0
44-Ru-99 b_c: 6.9(1.0) => | abs: => 6.9(1.0)
44-Ru-100 b_c: 0 => | inc: => 0 | abs: => 4.8(6)
44-Ru-101 b_c: 3.3(9) => | abs: => 3.3(9)
44-Ru-102 b_c: 0 => | inc: => 0 | abs: => 1.17(7)
44-Ru-104 b_c: 0 => | inc: => 0 | abs: => 0.31(2)
45-Rh-103 b_c: 5.88(4) => 5.90(4) | inc: E => 0.3(3)*
48-Cd b_c: 4.87(5) => 4.83(5)
48-Cd-106 abs: 1. => 1.0(2.0)
48-Cd-108 b_c: 5.4(1) => 5.31(24)
48-Cd-110 b_c: 5.9(1) => 5.78(8)
48-Cd-111 b_c: 6.5(1) => 6.47(8) | inc: E => 0.3(3)* | abs: 24(3.) => 24.0(5.0)
48-Cd-112 b_c: 6.4(1) => 6.34(6)
48-Cd-113 b_c: -8.0(2) => -8.0(1)
48-Cd-114 b_c: 7.5(1) => 7.48(5)
48-Cd-116 b_c: 6.3(1) => 6.26(9)
49-In-115 b_c: 4.01(2) => 4.00(3)
50-Sn-112 b_c: 6.1(1.) E => 6.0(1.0)* | abs: 1.01(11) => 1.00(11)
50-Sn-114 b_c: 6.2(3) => 6.0(3)
50-Sn-116 b_c: 5.93(5) => 6.10(1)
50-Sn-117 b_c: 6.48(5) => 6.59(8)
50-Sn-118 b_c: 6.07(5) => 6.23(4)
50-Sn-119 b_c: 6.12(5) => 6.28(3)
50-Sn-120 b_c: 6.49(5) => 6.67(4)
50-Sn-122 b_c: 5.74(5) => 5.93(3)
50-Sn-124 b_c: 5.97(5) => 6.15(3)
51-Sb-121 tot: 4.10(9) => 4.10(19)
52-Te b_c: 5.80(3) => 5.68(2) | inc: 0.09(1) => 0.09(6) | tot: 4.32(4) => 4.32(5) | abs: 4.05(5) => 4.7(1)
52-Te-120 tot: 3.4(7) => 3.5(7)
52-Te-124 b_c: 7.96(10) => 7.95(10)
52-Te-125 b_c: 5.02(8) => 5.01(8)
52-Te-126 b_c: 5.56(7) => 5.55(7)
52-Te-128 b_c: 5.89(7) => 5.88(8)
52-Te-130 b_c: 6.02(7) => 6.01(7)
54-Xe b_c: 4.92(3) => 4.69(4) | inc: => 0
56-Ba-135 b_c: 4.67(10) => 4.66(10)
56-Ba-136 b_c: 4.91(8) => 4.90(8)
56-Ba-137 b_c: 6.83(10) => 6.82(10)
56-Ba-138 b_c: 4.84(8) => 4.83(8)
57-La abs: 8.97(5) => 8.97(2)
58-Ce-136 b_c: 5.80(9) => 5.76(9)
58-Ce-138 b_c: 6.70(9) => 6.65(9)
58-Ce-140 b_c: 4.84(9) => 4.81(9)
58-Ce-142 b_c: 4.75(9) => 4.72(9)
60-Nd-143 b_c: 14.2(5) E => 14.0(2.0)* | abs: 334.(10.) => 337.0(10.0)
60-Nd-145 b_c: 14.2(5) => 14.0(2.0)*
60-Nd-150 b_c: 5.3(2) => 5.28(20)
62-Sm-154 b_c: 9.3(1.0) => 8.0(1.0)
65-Tb-159 b_c: 7.38(3) => 7.34(2)
66-Dy b_c: 16.9(2) => 16.9(3)
66-Dy-163 inc: 0.21(10) => 0.21(19)
67-Ho-165 b_c: 8.01(8) => 8.44(3)
68-Er-162 b_c: 8.8(2) => 9.01(11)
68-Er-164 b_c: 8.2(2) => 7.95(14)
68-Er-166 b_c: 10.6(2) => 10.51(19)
68-Er-168 b_c: 7.4(4) => 7.43(8)
68-Er-170 b_c: 9.6(5) => 9.61(6)
70-Yb-170 b_c: 6.77(10) => 6.8(1)
70-Yb-171 b_c: 9.66(10) => 9.7(1)
70-Yb-172 b_c: 9.43(10) => 9.5(1)
70-Yb-173 b_c: 9.56(7) => 9.56(10) | inc: 3.5(3) => 3.5 | tot: 15.0(4) => 15
70-Yb-176 b_c: 8.72(10) => 8.7(1)
71-Lu-175 b_c: 7.24(3) => 7.28(9)
73-Ta-180 inc: E => 0.5(5)*
74-W b_c: 4.86(2) => 4.755(18)
74-W-182 b_c: 6.97(14) => 7.04(4)
74-W-183 b_c: 6.53(4) => 6.59(4)
74-W-184 b_c: 7.48(6) => 7.55(6)
74-W-186 b_c: -0.72(4) => -0.73(4)
75-Re-187 inc: 1.0(8) => 1.0(6)
76-Os abs: 16.0(4) => 16.0(4.0)
76-Os-186 b_c: 11.6(1.7) => 12.0(1.7)
76-Os-187 inc: E => 0.3(3)*
76-Os-188 b_c: 7.6(3) => 7.8(3)
76-Os-189 b_c: 10.7(3) => 11.0(3)
76-Os-190 b_c: 11.0(3) => 11.4(3)
76-Os-192 b_c: 11.5(4) => 11.9(4)
77-Ir abs: 425.3(2.4) => 425.0(2.0)
78-Pt-195 b_c: 8.83(9) => 8.91(9)
79-Au-197 b_c: 7.63(6) => 7.90(7)
80-Hg b_c: 12.692(15) => 12.595(45)
80-Hg-201 abs: => 7.8(2.0)
80-Hg-202 b_c: => 11.002(43) | tot: => 15.2108(2)
81-Tl-203 b_c: 6.99(16) => 8.51(8)
81-Tl-205 b_c: 9.52(7) => 8.87(7)
82-Pb b_c: 9.405(3) => 9.401(2)
82-Pb-204 b_c: 9.90(10) => 10.893(78)
82-Pb-206 b_c: 9.22(5) => 9.221(78)
82-Pb-207 b_c: 9.28(4) => 9.286(16)
82-Pb-208 b_c: 9.50(2) => 9.494(30)
83-Bi-209 inc: 0.0084(10) => 0.0084(19)
92-U-235 b_c: 10.47(3) => 10.50(3)
92-U-238 b_c: 8.402(5) => 8.407(7)
94-Pu-238 b_c: 14.1(5) => | inc: 0 => | tot: 25.0(1.8) => | abs: 558.(7.) =>[PAK edits: removed spurious differences due to column alignment in online tables]
thamnos
commented
1 month ago I must say I found it surprising / unsettling as a user to get values that are different from the ones on https://www.ncnr.nist.gov/resources/n-lengths/list.html , which I am used to.
pkienzle
commented
1 month ago The data table from the Atominstitut (ATI) show the history of measurements for the bound coherent scattering lengths along with the measurement method and measurement uncertainty:
http://www.ati.ac.at/~neutropt/scattering/ScatteringLengths.PDFThe chosen value (in bold) is usually the most certain value, with exceptions such as 22-Ti where a more recent method was chosen with much greater uncertainty. I used this table when showing the differences from Sears in my comment above.
My take away is to not put too much faith in the sld values given the uncertainty in material composition, density and isotopic abundance, and in the neutron beam you are using to measure the scattering. I'm content to use them as starting values for a fit.
Another way to look at it: if the particular values had a strong effect on the measurement then we would have more digits in the table. Isotopic abundance variation alone limits you to about 0.1%.
Dawidowski, et al. have an updated version of the neutron cross section tables. The following lists the changes from the existing table values. There are changes to the coherent cross section (σ_coh) for many isotopes, but we use b_c instead of coh when computing SLD so I stripped these changes from the output. Also, I stripped energy-dependent isotopes and elements that appear in Lynn & Seeger.
Updated values:
Further restricting this to changes in values that will affect the sld calculations (b_c, abs, tot):
The reference does not cite sources for these changes.
[1] Dawidowski, J., Granada, J. R., Santisteban, 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. https://doi.org/10.1016/B978-0-12-398374-9.09989-7