# ENDF reaction MT's and macroscopic reaction numbers

Serpent uses standard ENDF reaction MTs to identify neutron and photon reactions. The numbers are used with detector response functions, microscopic cross section calculations and printed in various output files. Detector responses also include macroscopic cross sections (and similar), identified by negative reaction numbers.

Below are descriptive lists of ENDF reaction MTs and macroscopic reaction numbers. For more information on the MT numbers, see the ENDF Format Manual.[1] It should be noted that even though the notation is very similar to that used by MCNP, there are some differences in the definitions of some response functions.

## ENDF Reaction MTs

### Neutron reactions

MT Description Notes
1 (n,total) incident neutrons only (sum over MTs 2, 4, 5, 11, 16-18, 22-26, 28-37, 41-43, 44-45, 102-117)
2 (n,n0) elastic scattering
3 (n,nonelastic) nonelastic (sum over MTs 4, 5, 11, 16-18, 22-26, 28-37, 41-42, 44-45, 102-117) - redundant
4 (n,n) total inelastic scattering (incident neutrons); production of one neutron in the exit channel (sum over MTs 51 to 91) - redundant
5 (n,anything) sum of all reactions not given explicitly in another MT number, used for lumping together multiple reaction modes
11 (n,2nd) production of two neutrons and a deuteron, plus a residual if any
16 (n,2n) production of two neutrons, plus a residual (if any) - some nuclides miss MT 16 and have only MTs 875-891 instead
17 (n,3n) production of three neutrons, plus a residual (if any)
18 (n,fission) total fission (sum over MTs 19-21 and 38)
19 (n,f) 1st-chance fission
20 (n,nf) 2nd-chance fission
21 (n,2nf) 3rd-chance fission
22 (n,nα) production of a neutron and an alpha particle, plus a residual (if any)
23 (n,n3α) production of a neutron and three alpha particles, plus a residual (if any)
24 (n,2nα) production of two neutron and an alpha particle, plus a residual (if any)
25 (n,3nα) production of three neutrons and an alpha particle, plus a residual (if any)
27 (z,abs) absorption (sum over MTs 18 and 102-117)- redundant
28 (n,np) production of a neutron and a proton, plus a residual (if any)
29 (n,n2α) production of a neutrons and two alpha particles, plus a residual (if any)
30 (n,2n2α) production of two neutrons and two alpha particles, plus a residual (if any)
32 (n,nd) production of a neutron and a deuteron, plus a residual (if any)
33 (n,nt) production of a neutron and a triton, plus a residual (if any)
34 (n,n3He) production of a neutron and a 3He particle, plus a residual (if any)
35 (n,nd2α) production of a neutron, a deuteron and two alpha particles, plus a residual (if any)
36 (n,nt2α) production of a neutron, a triton, and two alpha particles, plus a residual (if any)
37 (n,4n) production of four neutrons, plus a residual (if any)
38 (n,3nf) 4th-chance fission
41 (n,2np) production of two neutrons and a proton, plus a residual (if any)
42 (n,3np) production of three neutrons and a proton, plus a residual (if any)
44 (n,n2p) production of a neutron and two protons, plus a residual (if any)
45 (n,npα) production of a neutron, a proton and an alpha particle, plus a residual (if any)
51-90 (z,ni inelastic scattering to excited states; production of a neutron leaving the residual nucleus in the ith excited state (i = 1, 2,...,40)
91 (n,nc) inelastic scattering to continuum; production of a neutron in the continuum not included in the above discrete representation
101 (n,disap) total absorption or dissaparance (sum over MTs 102-117) - redundant
102 (n,γ) radiative capture (102g/102m for transmutation to ground/isomeric state)
103 (n,p) production of a proton (sum over MTs 600-647, if present), plus a residual (if any)
104 (n,d) production of a deuteron (sum over MTs 650-699, if present), plus a residual (if any)
105 (n,t) production of a triton (sum over MTs 700-749, if present), plus a residual (if any)
106 (n,3He) production of a 3He particle (sum over MTs 750-799, if present), plus a residual (if any)
107 (n,α) production of an alpha particle (sum over MTs 800-849, if present), plus a residual (if any)
108 (n,2α) production of two alpha particles, plus a residual (if any)
109 (n,3α) production of three alpha particles, plus a residual (if any)
111 (n,2p) production of two protons, plus a residual (if any)
112 (n,pα) production of a proton and an alpha particle, plus a residual (if any)
113 (n,t2α) production of a triton and two alpha particles, plus a residual (if any)
114 (n,d2α) production of a deuteron and two alpha particles, plus a residual (if any)
115 (n,pd) production of proton and a deuteron, plus a residual (if any)
116 (n,pt) production of a proton and a triton, plus a residual (if any)
117 (n,dα) production of a deuteron and an alpha particle, plus a residual (if any)
201 (n,totneutron) total neutron production (use -6 instead); sum of the cross section times the particle implicit/explicit yield over all reactions (ex. elastic scattering) at final stage.
202 (n,totphoton) total photon production; sum of the cross section times the particle implicit/explicit yield over all reactions (ex. elastic scattering) at final stage.
203 (n,totproton) total proton production; sum of the cross section times the particle implicit/explicit yield over all reactions (ex. elastic scattering) at final stage.
204 (n,totdeuteron) total deuteron production; sum of the cross section times the particle implicit/explicit yield over all reactions (ex. elastic scattering) at final stage.
205 (n,tottriton) total triton production; sum of the cross section times the particle implicit/explicit yield over all reactions (ex. elastic scattering) at final stage.
206 (n,tot3He) total 3He production; sum of the cross section times the particle implicit/explicit yield over all reactions (ex. elastic scattering) at final stage.
207 (n,totα) total α production; sum of the cross section times the particle implicit/explicit yield over all reactions (ex. elastic scattering) at final stage.
301 (n,totheat) total heat production; total heating number multiplied by total cross section (note difference to MCNP)
443 (n,kinkerma) kinematic KERMA - Note to developers: check if this needs to be multiplied by total xs
444 (n,damenergy) damage-energy production - Note to developers: check if this needs to be multiplied by total xs
600 (n,p0) production of a proton, leaving the residual nucleus in the ground state - MTs 600-649 can be used to replace MT 103
601-648 (n,pi) production of a proton, leaving the residual nucleus in the ith excited state (i = 1,2,...,48)
649 (n,pc) production of a proton the continuum not included in the above discrete representation
650 (n,d0) production of a deuteron, leaving the residual nucleus in the ground state - MTs 650-699 can be used to replace MT 104
651-698 (n,di) production of a deuteron, leaving the residual nucleus in the ith excited state (i = 1,2,...,48)
699 (n,dc) production of a deuteron in the continuum not included in the above discrete representation
700 (n,t0) production of a triton, leaving the residual nucleus in the ground state - MTs 700-749 can be used to replace MT 105
701-748 (n,ti) production of a triton, leaving the residual nucleus in the ith excited state (i = 1,2,...,48)
749 (n,tc) production of a triton in the continuum not included in the above discrete representation
750 (n,3He0) production of a3He particle, leaving the residual nucleus in the ground state - MTs 750-799 can be used to replace MT 106
751-798 (n,3Hei) production of a 3He particle, leaving the residual nucleus in the ith excited state (i = 1,2,...,48)
799 (n,3Hec) production of a3He particle in the continuum not included in the above discrete representation
800 (n,α0) production of an alpha particle, leaving the residual nucleus in the ground state - MTs 800-849 can be used to replace MT 107
801 - 848 (n,αi) production of an alpha particle, leaving the residual nucleus in the ith excited state (i = 1,2,...,48)
849 (n,αc) production of an alpha particle in the continuum not included in the above discrete representation
875 (n,2n0) production of a neutron, leaving the residual nucleus in the ground state - MTs 875-891 can be used to replace MT 16
876-890 (n,2ni) production of a neutron, leaving the residual nucleus in the ith excited state (i = 1,2,...,48)
891 (n,2nc) production of a neutron in the continuum not included in the above discrete representation
1002 S(α,β) elastic scattering - not an official ENDF MT number
1004 S(α,β) inelastic scattering - not an official ENDF MT number

### Photon reactions

MT Description Notes
301 average heating number
502 Rayleigh scattering
504 Compton scattering
516 pair production
522 photoelectric effect

## Macroscopic reaction numbers

### Neutron reactions

Reaction # Description Notes
-1 macroscopic total cross section
-2 macroscopic total capture cross section sum of all reactions that do not produce secondary neutrons
-3 macroscopic total elastic scattering cross section
-4 macroscopic total heating cross section equivalent with the F8 tally in MCNP
-5 macroscopic total photon production cross section
-6 macroscopic total fission cross section
-7 macroscopic total fission neutron production cross section $\nu\Sigma_\mathrm{f}$
-8 macroscopic total fission energy production cross section $\kappa\Sigma_\mathrm{f}$
-9 majorant cross section
-10 macroscopic scattering recoil energy production cross section calculated from neutron energy loss in elastic and inelastic scattering
-11 source rate
-15 neutron density flux multiplied by inverse neutron speed
-16 macroscopic total scattering neutron production cross section
-30 temperature majorant cross section majorant used for rejetion sampling in TMS
-53 macroscopic proton production cross section
-54 macroscopic deuteron production cross section
-55 macroscopic triton production cross section
-56 macroscopic He-3 production cross section
-57 macroscopic He-4 production cross section
-80 total energy deposition combines responses for fission heating, neutron heating based on KERMA coefficients and analog photon heating
-100 user-defined response function followed by a function name corresponding to a function defined using the fun card, response material is omitted

### Photon reactions

Reaction # Description Notes
-9 majorant cross section Note to developers: check that this really works
-11 source rate Note to developers: check that this really works
-12 analog photon heating Energy deposition detector
-15 photon density flux multiplied by 1/c (Note to developers: check that this really works)
-25 macroscopic total cross section Note to developers: use -1 instead?
-26 macroscopic total heating cross section Note to developers: use -4 instead?
-27 photon pulse-height detector see detailed description
-100 user-defined response function followed by a function name corresponding to a function defined using the fun card, response material is omitted
-200 photon dose rate in local material in Gy/h, using mass attenuation coefficients from NIST data,[2] see detailed description
-201 photon dose rate in A-150 Tissue-Equivalent Plastic Reaction numbers -201 to -248 are reserved for photon dose rates in pre-defined material compositions using same data as -200
-202 photon dose rate in adipose Tissue (ICRU-44)
-203 photon dose rate in air, Dry (Near Sea Level)
-204 photon dose rate in alanine
-205 photon dose rate in B-100 Bone-Equivalent Plastic
-206 photon dose rate in bakelite
-207 photon dose rate in blood, Whole (ICRU-44)
-208 photon dose rate in bone, Cortical (ICRU-44)
-209 photon dose rate in brain, Grey/White Matter (ICRU-44)
-210 photon dose rate in breast Tissue (ICRU-44)
-211 photon dose rate in C-552 Air-equivalent Plastic
-212 photon dose rate in calcium Sulfate
-213 photon dose rate in 15 mmol/l Ceric Ammonium Sulfate Solution
-214 photon dose rate in cesium Iodide
-215 photon dose rate in concrete, Barite (Type BA)
-216 photon dose rate in concrete, Ordinary
-217 photon dose rate in eye Lens (ICRU-44)
-218 photon dose rate in calcium Fluoride
-219 photon dose rate in ferrous Sulfate (Standard Fricke)
-220 photon dose rate in gadolinium Oxysulfide
-221 photon dose rate in gafchromic Sensor
-222 photon dose rate in gallium Arsenide
-223 photon dose rate in glass, Lead
-224 photon dose rate in photographic Emulsion (Kodak Type AA)
-225 photon dose rate in lithium Fluride
-226 photon dose rate in lithium Tetraborate
-227 photon dose rate in lung Tissue (ICRU-44)
-228 photon dose rate in magnesium Tetroborate
-229 photon dose rate in mercuric Iodide
-230 photon dose rate in muscle, Skeletal
-231 photon dose rate in polyethylene Terephthalate (Mylar)
-232 photon dose rate in radiochromic Dye Film (Nylon Base)
-233 photon dose rate in ovary (ICRU-44)
-234 photon dose rate in photographic Emulsion (Standard Nuclear)
-235 photon dose rate in polymethyl Methacrylate
-236 photon dose rate in polyethylene
-237 photon dose rate in polystyrene
-238 photon dose rate in polyvinyl Chloride
-239 photon dose rate in glass, Borosilicate (Pyrex)
-240 photon dose rate in polytetrafluoroethylene (Teflon)
-241 photon dose rate in cadmium Telluride
-242 photon dose rate in tissue-Equivalent Gas (Methane Based)
-243 photon dose rate in tissue-Equivalent Gas (Propane Based)
-244 photon dose rate in testis (ICRU-44)
-245 photon dose rate in tissue, Soft (ICRU Four-Component)
-246 photon dose rate in tissue, Soft (ICRU-44)
-247 photon dose rate in plastic Scintillator (Vinyltoluene)
-248 photon dose rate in water, Liquid

## References

1. ^ Herman, M. and Trkov, A. "ENDF-6 Formats Manual." CSEWG Document ENDF-102 / BNL-90365-2009.
2. ^ Hubbell, J. H. and Seltzer, S.M. "Tables of X-Ray Mass Attenuation Coefficients and Mass Energy-Absorption Coefficients." (version 1.4). http://www.nist.gov/pml/data/xraycoef/