View source for Default isomeric branching ratios

Branching ratios to isomeric states are used in burnup calculation for the production of long-lived meta-stable nuclides, such as <sup>241m</sup>Am or <sup>148m</sup>Pm. The data is not available in ACE format cross section libraries and must therefore be obtained elsewhere. Serpent provides three options for defining the branching ratios:
#Use of default constant ratios (see table below)
#Use of user-defined constant ratios (see the [[Input syntax manual#set isobra|set isobra]] option)
#Use of energy-dependent ratios read from ENDF format files (see the [[Input syntax manual#set bralib|set bralib]] option)
User-defined constant ratios override the default values, energy-dependent data overrides constant ratios. 

== Default data ==

The default constant branching ratios from update 2.1.27 on are listed below. The values are calculated from energy-dependent branching ratios in the JEFF-3.1 activation file in PWR flux spectrum. The last two columns refer to ground-state and isomeric-state fractions, respectively.

{|class="wikitable" style="text-align: left;"
! Nuclide
! ZAI
! MT
! Frac. (g)
! Frac. (m)
|-
|Na-23
|110230
|102
|0.23200
|0.76800
|-
|Cl-37
|170370
|102
|0.88090
|0.11910
|-
|Sc-45
|210450
|102
|0.55600
|0.44400
|-
|Co-59
|270590
|102
|0.44400
|0.55600
|-
|Ge-72
|320720
|102
|0.50120
|0.49880
|-
|Ge-74
|320740
|102
|0.66600
|0.33400
|-
|Ge-76
|320760
|102
|0.40050
|0.59950
|-
|Se-76
|340760
|102
|0.74090
|0.25910
|-
|Se-78
|340780
|102
|0.11780
|0.88220
|-
|Se-80
|340800
|102
|0.84540
|0.15460
|-
|Se-82
|340820
|102
|0.14020
|0.85980
|-
|Br-79
|350790
|102
|0.76870
|0.23130
|-
|Br-81
|350810
|102
|0.09140
|0.90860
|-
|Kr-78
|360780
|102
|0.97040
|0.02960
|-
|Kr-80
|360800
|102
|0.60310
|0.39690
|-
|Kr-82
|360820
|102
|0.33300
|0.66700
|-
|Kr-84
|360840
|102
|0.18390
|0.81610
|-
|Rb-85
|370850
|102
|0.87910
|0.12090
|-
|Sr-84
|380840
|102
|0.25300
|0.74700
|-
|Sr-86
|380860
|102
|0.19880
|0.80120
|-
|Y-89
|390890
|102
|0.99790
|0.00210
|-
|Y-90
|390900
|102
|0.74960
|0.25040
|-
|Nb-93
|410930
|102
|0.31010
|0.68990
|-
|Nb-94
|410940
|102
|0.96100
|0.03900
|-
|Mo-92
|420920
|102
|0.99780
|0.00220
|-
|Rh-103
|451030
|102
|0.92400
|0.07600
|-
|Rh-105
|451050
|102
|0.90400
|0.09600
|-
|Pd-106
|461060
|102
|0.95270
|0.04730
|-
|Pd-108
|461080
|102
|0.97790
|0.02210
|-
|Pd-110
|461100
|102
|0.85000
|0.15000
|-
|Ag-107
|471070
|102
|0.98980
|0.01020
|-
|Ag-109
|471090
|102
|0.95400
|0.04600
|-
|Cd-110
|481100
|102
|0.99450
|0.00550
|-
|Cd-112
|481120
|102
|0.86850
|0.13150
|-
|Cd-114
|481140
|102
|0.88120
|0.11880
|-
|Cd-116
|481160
|102
|0.66600
|0.33400
|-
|In-113
|491130
|102
|0.41910
|0.58090
|-
|Sn-112
|501120
|102
|0.72530
|0.27470
|-
|Sn-116
|501160
|102
|0.95680
|0.04320
|-
|Sn-118
|501180
|102
|0.97940
|0.02060
|-
|Sn-120
|501200
|102
|0.98750
|0.01250
|-
|Sn-122
|501220
|102
|0.01120
|0.98880
|-
|Sn-124
|501240
|102
|0.03750
|0.96250
|-
|Sn-126
|501260
|102
|0.30180
|0.69820
|-
|Sb-121
|511210
|102
|0.93690
|0.06310
|-
|Te-120
|521200
|102
|0.88710
|0.11290
|-
|Te-122
|521220
|102
|0.64480
|0.35520
|-
|Te-124
|521240
|102
|0.99120
|0.00880
|-
|Te-126
|521260
|102
|0.86890
|0.13110
|-
|Te-128
|521280
|102
|0.92450
|0.07550
|-
|Te-130
|521300
|102
|0.85590
|0.14410
|-
|Te-132
|521320
|102
|0.85170
|0.14830
|-
|I-129
|531290
|102
|0.41300
|0.58700
|-
|I-131
|531310
|102
|0.98390
|0.01610
|-
|Xe-124
|541240
|102
|0.83000
|0.17000
|-
|Xe-126
|541260
|102
|0.86910
|0.13090
|-
|Xe-128
|541280
|102
|0.89230
|0.10770
|-
|Xe-130
|541300
|102
|0.91640
|0.08360
|-
|Xe-132
|541320
|102
|0.88670
|0.11330
|-
|Xe-133
|541330
|102
|0.96000
|0.04000
|-
|Xe-134
|541340
|102
|0.98530
|0.01470
|-
|Cs-133
|551330
|102
|0.90700
|0.09300
|-
|Cs-134
|551340
|102
|0.99600
|0.00400
|-
|Cs-135
|551350
|102
|0.98400
|0.01600
|-
|Cs-137
|551370
|102
|0.90210
|0.09790
|-
|Ba-130
|561300
|102
|0.88710
|0.11290
|-
|Ba-132
|561320
|102
|0.91750
|0.08250
|-
|Ba-134
|561340
|102
|0.92630
|0.07370
|-
|Ba-135
|561350
|102
|0.99780
|0.00220
|-
|Ba-136
|561360
|102
|0.97310
|0.02690
|-
|Ce-136
|581360
|102
|0.86620
|0.13380
|-
|Ce-138
|581380
|102
|0.97870
|0.02130
|-
|Pr-141
|591410
|102
|0.65190
|0.34810
|-
|Pr-143
|591430
|102
|0.31000
|0.69000
|-
|Pm-147
|611470
|102
|0.53300
|0.46700
|-
|Eu-153
|631530
|102
|0.98400
|0.01600
|-
|Dy-164
|661640
|102
|0.37000
|0.63000
|-
|Ho-165
|671650
|102
|0.94900
|0.05100
|-
|Er-166
|681660
|102
|0.25030
|0.74970
|-
|Lu-175
|711750
|102
|0.33310
|0.66690
|-
|Lu-176
|711760
|102
|0.99900
|0.00100
|-
|Hf-179
|721790
|102
|0.99100
|0.00900
|-
|W-182
|741820
|102
|0.86990
|0.13010
|-
|W-184
|741840
|102
|0.99830
|0.00170
|-
|Re-185
|751850
|102
|0.99900
|0.00100
|-
|Re-187
|751870
|102
|0.97290
|0.02710
|-
|Au-197
|791970
|102
|0.99900
|0.00100
|-
|Hg-196
|801960
|102
|0.96600
|0.03400
|-
|Hg-198
|801980
|102
|0.99180
|0.00820
|-
|Pb-206
|822060
|102
|0.97830
|0.02170
|-
|Bi-209
|832090
|102
|0.67910
|0.32090
|-
|Pa-233
|912330
|102
|0.48710
|0.51290
|-
|U-234
|922340
|102
|0.50000
|0.50000
|-
|Np-235
|932350
|102
|0.40000
|0.60000
|-
|Np-239
|932390
|102
|0.35730
|0.64270
|-
|Pu-236
|942360
|102
|0.50010
|0.49990
|-
|Am-241
|952410
|102
|0.91900
|0.08100
|-
|Am-243
|952430
|102
|0.06260
|0.93740
|-
|Bk-247
|972470
|102
|0.40000
|0.60000
|-
|Es-253
|992530
|102
|0.03200
|0.96800
|-
|Es-255
|992550
|102
|0.98400
|0.01600
|-
|}

= Calculating branching ratios from energy-dependent data =

Calculating branching ratios from energy-dependent data is relatively easy using standard detectors. For example, the capture fractions of <sup>241</sup>Am to ground and metastable state of <sup>242</sup>Am can be obtained with detector input:

 <nowiki>
% --- Detector material:

mat Am241 1.0 95241.09c 1.0

% --- Detector: (reaction rates using spectrum in material "fuel")

det 1
dm fuel
dr 102 Am241 dr 102g  Am241 dr 102m  Am241
</nowiki>

Branching ratios to ground and metastable states can then be obtained by dividing the results in the 2nd and 3rd detector bin with the result of the first bin. The ground state fraction can then be used as the input for the [[Input syntax manual#set isobra|set isobra]] card.

For a complete example, see:
* [[Branching ratio example|Serpent input file and post-processing script]]
* [http://virtual.vtt.fi/virtual/montecarlo/misc/sss_jeff31a.bra Energy-dependent branching data from JEFF-3.1 activation file]