MOSCOW STATE UNIVERSITY, INSTITUTE OF NUCLEAR PHYSICS

CENTRE FOR PHOTONUCLEAR EXPERIMENTS DATA


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BNL-NCS-63380-00/05-REV.

EXFOR Basics
A Short Guide to the Nuclear Reaction Data Exchange Format

Victoria McLane
National Nuclear Data Center
on behalf of the
Nuclear Data Center Network

May 2000

Brookhaven National Laboratory
Upton, NY 11973-5000

Table of Contents

INTRODUCTION

This manual is intended as a guide to users of nuclear reaction data compiled in the EXFOR format, and is not intended as a complete guide to the EXFOR System.

EXFOR is the exchange format designed to allow transmission of nuclear reaction data between the Nuclear Reaction Data Centers. In addition to storing the data and its' bibliographic information, experimental information is also compiled. The status (e.g., the source of the data) and history (e.g., date of last update) of the data set is also included.

EXFOR is designed for flexibility in order to meet the diverse needs of the nuclear reaction data centers. It was originally conceived for the exchange of neutron data and was developed through discussions among personnel from centers situated in Saclay, Vienna, Livermore and Brookhaven. It was accepted as the official exchange format of the neutron data centers at Saclay, Vienna, Brookhaven and Obninsk, at a meeting held in November 1969. As a result of two meetings held in 1975 and 1976 and attended by several charged-particle data centers, the format was further developed and adapted to cover all nuclear reaction data.

The exchange format should not be confused with a center-to-user format. Although users may obtain data from the centers in the EXFOR format, other center-to-user formats have been developed to meet the needs of the users within each center's own sphere of responsibility.

The EXFOR format, as outlined, allows a large variety of numerical data tables with explanatory and bibliographic information to be transmitted in a format:

  • that is machine-readable (for checking and indicating possible errors);
  • that can be read by personnel (for passing judgement on and correcting errors).

The data presently included in the EXFOR exchange file include:

  • a "complete" compilation of experimental neutron-induced reaction data,
  • a selected compilation of charged-particle-induced reaction data,
  • a selected compilation of photon-induced reaction data.

EXCHANGE FILE FORMAT

An exchange file contains a number of entries (works). Each entry is divided into a number of subentries (data sets). Each entry is assigned an accession number; each subentry is assigned a subaccession number (the accession number plus a subentry number). The subaccession numbers are associated with a data table throughout the life of the EXFOR system.

The subentries are further divided into:

  • bibliographic, descriptive and bookkeeping information (hereafter called BIB information),
  • common data that applies to all data throughout the subentry ,and
  • a data table.

The file may, therefore, be considered to be of the following form:

In order to avoid repetition of information that is common to all subentries within an entry or to all lines within a subentry, information may be associated with an entire entry or with an entire subentry. To accomplish this, the first subentry of each work contains only information that applies to all other subentries. Within each subentry, the information common to all lines of the table precedes the table. Two levels of hierarchy are thereby established:

Permitted Character Set. The following characters are permitted for use in the exchange format:

  • All Roman characters, A to Z and a to z
  • All numbers, 0 to 9
  • The special characters:
+(plus)>(greater than)
-(minus):(colon)
.(decimal point/full stop);(semi-colon)
)(right parenthesis)!(exclamation mark)
((left parenthesis)?(question mark)
*(asterisk)&(ampersand)
/(slash)#(number symbol)
=(equals)[(opening bracket)
'(apostrophe)](closing bracket)
,(comma)"(quotation mark)
%(percent)~(varies as sign)
<(less than)@(at symbol)

EXFOR Records EXFOR Exchange files consist of 80 character ASCII records. The format of columns 1-66 varies according to the record type as outlined in the following chapters. Columns 67-79 is used to uniquely identify a record within the file. The records on the file are in ascending order according to the record identification. Column 80 is reserved for an alteration flag.

Record identification. The record identification is divided into three fields: the accession number (entry), subaccession number (subentry), and record number within the subentry. The format of these fields is as follows.

Columns 67-71Center-assigned accession number
72-74Subaccession number
75-79Sequence number

Alteration flag (column 80). The last column of each record contains the alteration flag which is used to indicate that a record and/or following records has been altered (i.e., added, deleted or modified) since the work was last transmitted. The flag field will normally contain a blank to indicate an unaltered record.

System Identifiers Each of the sections of an EXFOR file begins and ends with a system identifier. Each of the following system identifiers indicates the beginning of one of these sections.

TRANS- A file is the unit
ENTRY- An entry is the unit
SUBENT- A subentry is the unit
BIB- A BIB Information section is the unit
COMMON- A common data section is the unit
DATA- A data table section is the unit
  • The end of unit is signaled by modifier END preceding the basic system identifier, e.g., NODATA.
  • A positive indication that a unit is intentionally omitted is signaled by the modifier NO preceding the basic system identifier, e.g., NOSUBENT.

The following system identifiers are defined.

  1. An file is:
Headed by:TRANScxxxyyyymmdd

CXXX = the center-identification character,

yyyymmdd = date (year, month, and day) on which the was generated.

Ended by:ENDTRANSN1 

N1 = number of entries (accession numbers) on the file.

2. An entries is:
Headed by:ENTRYN1N2

N1 = 5-character accession number

N2 = Date of last update (or date of entry if never updated) (yyyymmdd)

Ended by:ENDENTRYN1 

N1 - The number of subentries in the work.

N2 - Presently unused (may be blank or zero).

3. A subentry is:
Headed by:SUBENTN1N2

N1 = 8-character subaccession number (accession number and subentry number).

N2 = Date of last update (or date of entry if never updated) (yyyymmdd).

Ended by:ENDSUBENTN1 

N1 - The number of records within the subentry.

If a subentry has been deleted, the following record is included in the file
 NOSUBENTN1N2

N1 = 8-character subaccession number.

N2 = Date of last alter.

4.A BIB section is:
Headed byBIBN1N2

N1 =Number of information-identifier keywords in the BIB section.

N2 = Number of records in the BIB section.

Ended by :ENDBIBN1 

N1 - Number of records in BIB section.

If no BIB section is given the following record is included:

NOBIB

5. A COMMON section is:
Headed by:COMMONN1N2

N1 = Number of common data fields.

N2 = Number of records within the common section.

Ended by:ENDCOMMONN1 

N1 = Number of records within the common section.

If no COMMON section is given, the following record is included:

NOCOMMON

6. A DATA section is:
Headed by:DATAN1N2

N1 = Number of fields (variables) associated with each line of a data table.

N2 = Number of data lines within the table (excluding headings and units).

Ended by:ENDDATAN1N2

N1 - Number of records within the data section.

If no DATA section is given, the following record is included:

NODATA

POINTERS

Different pieces of EXFOR information may be linked together by pointers. A pointer is a numeric or alphabetic character (1,2...9,A,B,...Z) placed in the eleventh column of the information-identifier keyword field in the BIB section and in the field headings in the COMMON or DATA section.

Pointers may link, for example,

  • one of several reactions with its data field;
  • one of several reactions with a specific piece of information in the BIB section (e.g., ANALYSIS), and/or with a value in the COMMON section, and/or with a field in the DATA section;
  • a value in the COMMON section with any field in the DATA section.

In general, a pointer is valid for only one subentry. A pointer used in the first subentry applies to all subentries and has a unique meaning throughout the entire entry.

BIB SECTION

The BIB section contains the bibliographic information (e.g., reference, authors), descriptive information (e.g., neutron source, method, facility), and administrative information (e.g., history) associated with the data presented. It is identified on an exchange file as that information between the system identifiers BIB and ENDBIB.

A BIB record consists of three parts:

columns 1-11:information-identifier keyword field,
columns 12-66:information field, which may contain coded information and/or free text,
columns 67-80:record identification and alteration flag fields.

BIB information for a given data set consists of the information contained in the BIB section of its subentry together with the BIB information in subentry 001. That is, information coded in subentry 001 applies to all other subentries in the same entry. A specific information-identifier keyword may be included in either subentry or both.

Information-identifier keywords The information-identifier keyword is used to define the significance of the information given in columns 12-66. The keyword is left adjusted to begin in column 1, and does not exceed a length of 10 characters (column 11 is either blank, or contains a pointer, see Chapter 5).

These keywords may, in general, appear in any order within the BIB section, however, an information-identifier keyword is not repeated within any one BIB section. If pointers are present, they appear on the first record of the information to which they are attached and are not repeated on continuation records. A pointer is assumed to refer to all BIB information until either another pointer or a new keyword is encountered. As this implies, pointer-independent information for each keyword appears first.

Coded (machine-retrievable) information Coded information may be used:

  • to define the actual BIB information,
  • as a link to the COMMON and DATA section,
  • to enter associated numerical data.

Coded information is enclosed in parentheses and left adjusted so that the opening parenthesis appears in column 12. Several pieces of coded information may be associated with a given information-identifier keyword.

Codes for use with a specific keyword are found in the relevant dictionary. However, for some keywords, the code string may include retrievable information other than a code from one of the dictionaries.

In general, codes given in the dictionaries may be used singly or in conjunction with one or more codes from the same dictionary. Two options exist if more than one code is used:
a)two or more codes within the same set of parenthesis, separated by a comma; for example;
b)each code on a separate record, enclosed in it's own set of parenthesis starting in column 12, followed by free text.

For some cases, the information may be continued onto successive records. Information on continuation records does not begin before column 12 (columns 1-10 are blank and column 11 is blank or contains a pointer).

Note that some information-identifier keywords have no coded information associated with them and that, for many keywords which may have coded information associated with them, it need not always be present.

Free text Free text may be entered in columns 12-66 under each of the information-identifier keywords in the BIB section. The text follows any coded information on the record or may begin on a separate record; it may be continued onto any number of records.

The language of the free text is English.

Coding of nuclides and compounds. Nuclides appear in the coding of many keywords. The general code format is Z-S-A-X, where:

Zis the charge number; up to 3 digits, no leading zeros
Sis the element symbol; 1 or 2 characters (Dictionary 8)
Ais the mass number; up to 3 digits, no leading zeroes. A single zero denotes natural isotopic composition.
X is an isomer code denoting the isomeric state this subfield is not used if there are no known isomeric states.
 X may have the following values:
 Gfor ground state (of a nucleus which has a metastable state)
 Mif only one metastable state is regarded
  M1for the first metastable state
 M2for the second, etc.
 Tfor sum of all isomers (limited to use within an isomeric ratio in SF4 of the reaction string)
Examples:92-U-235
49-IN-115-M/T

Compounds may in some cases replace the nuclide code. The general format for coding compounds is either the specific compound code, taken from Dictionary 9, or the general code for a compound of the form Z-S-CMP.

Example: 26-FE-CMP

COMMON AND DATA SECTIONS

A data table is, generally, a function of one or more independent variables, e.g.,

  • X vs. Y, e.g., energy, cross section
  • X, X' and Y, e.g., energy and angle; differential cross section
  • X, X' and X" vs. Y, e.g., energy, secondary energy, angle, partial angular distribution.

When more than one representation of Y is present, the table may be X vs. Y and Y', with associated errors for X, Y and Y' (e.g., X = energy, Y = absolute cross section, Y' = relative cross section), and possible associated information. The criteria for grouping Y with Y' are that they both be derived from the same experimental information by the author of the data.

For some data, the data table does not have an independent variable X but only a function Y. (Examples: Spontaneous ν resonance energies without resonance parameters)

Additional variables may be associated with the data, e.g., errors, standards.

The format of the common data (COMMON) and data table (DATA) sections is identical. Each section is a table of data containing the data headings and units associated with each field. The difference between the common data and data table is:

  • The common data contains constant parameters that apply to each line of a point data table;
  • The data table contains fields of information; each field, generally, contains values as a function of one or more independent variables (e.g., angle, angular error, cross section, cross section error), i.e., one or more lines of data.

Each physical record may contain up to six information fields, each 11 columns wide. If more than six fields are used, the remaining information is contained on the following records. Therefore, a data line consists of up to three physical records. The number of fields in a data line is restricted to 18.

Records are not packed; rather, individual point information is kept on individual records; i.e., if only four fields are associated with a data line, the remaining two fields are left blank, and, in the case of the data table, the information for the next line begins on the following record. These rules also apply to the headings and units associated with each field.

The content of the COMMON and DATA sections are as follows:

  • Field headings: a data heading left adjusted to the beginning of each field (columns 1, 12, 23, 34, 45, 56), plus, perhaps, a pointer placed in the last (11th) column of a field.
  • Data units: left adjusted to the beginning of each field (columns 1, 12, 23, 34, 45, 56).
  • Numerical data: FORTRAN-readable using a floating-point format, as follows.
    • A decimal point is always present, even for integers.
    • A decimal number without an exponent can have any position within the 11-character field.
    • No blank is allowed following a sign (+ or -).
    • A plus sign may be omitted, except that of an exponent when there is no E.
    • In an exponential notation, the exponent is right adjusted within the 11-character field. The mantissa may have any position.

The values are either zero or have absolute values between 1.0000E-38 and 9.999E+38.

COMMON Section The COMMON section is identified as that information between the system identifiers COMMON and ENDCOMMON. In the common data table, only one value is entered for a given field, and successive fields are not integrally associated with one another.

An example of a common data table with more than 6 fields:
11223 344556 66
COMMON 
ENEN-ERREN-RSLE-LVLE-LVLMONIT
MPNIT-ERR 
MEVMEVMEVMEVMEVMB
MB 
2.730.020.052.732.783.456
0.123 
ENDCOMMON 

DATA Section The DATA section is identified as that information between the system identifiers DATA and ENDDATA. In the DATA table, all entries on a record are integrally associated with an individual point. Independent variables precede dependent variables, and are monotonic until the value of the preceding independent variable, if any exist, changes.

Every line in a data table gives data information. This means, for example, that a blank in a field headed DATA is permitted only when another field contains the data information on the same line, e.g., under DATA-MAX. In the same way, each independent variable occurs at least once in each line (e.g., either under data headings E-LVL or E-LVL-MIN, E-LVL-MAX, see example following). Supplementary information, such as resolution or standard values, is not given on a line of a data table unless the line includes data information. Blanks are permitted in all fields.

An example of a point data table is shown below with its associated DATA and ENDDATA records.
11223 344556 66
DATA 
ANGANG-ERRDATADATA-ERRDATA-MAX 
ADEGADEGMB/SRMB/SRMB/SR 
10.71.8138.8.5 
22.91.2127.4.2 
39.10.9 83.2  
46.70.714.82.9 
ENDDATA

Appendix: Information Identifier Keywords

This appendix provides a listing of all information-identifier keywords, along with details about their use. The keywords appear in alphabetical order.

ADD-RES.   Gives information about any additional results obtained in the experiment, but which are not compiled in the data tables. Codes are given in Dictionary 20.

Example:ADD-RES(RANGE) Range of recoils measured.

ANALYSIS.   Gives information as to how the experimental results have been analyzed to obtain the values given under the heading DATA which actually represent the results of the analysis. Codes are found in Dictionary 23.
Example:ANLAYSIS(MLA) Breit-Wigner multilevel analysis

ASSUMED   Gives information about values assumed in the analysis of the data, and about COMMON or DATA fields headed by ASSUM or its derivatives. The format of the code is: (heading,reaction,quantity)

Heading field: data heading to be defined.

Reaction field and quantity field: coded as under the keyword REACTION.

Example:ASSUMED(ASSUM,6-C-12(N,TOT),,SIG)

AUTHOR.   Gives the authors of the work reported.
Example: AUTHOR(R.W.McNally Jr,A.B.JONES)

COMMENT.   Gives pertinent information which cannot logically be entered under any other of the keywords available.

CORRECTION.   Gives information about corrections applied to the data in order to obtain the values given under DATA. See also LEXFOR, Correction.

COVARIANCE.   Gives covariance information provided by the experimentalist, or to flag the existence of a covariance data file. See Appendix D for covariance file format.

Example:COVARIANCE(COVAR) COVARIANCE FILE EXISTS AND MAY BE OBTAINED ON REQUEST.

CRITIQUE.   Gives comments on the quality of the data presented in the data table.

DECAY-DATA.   Gives the decay data for any nuclide occurring in the reaction measured as assumed or measured by the author for obtaining the data given . The general format of the coding string consists of three major fields which may be preceded by a decay flag: ((decay flag)nuclide,half-life,radiation).

Flag. A fixed-point number that also appears in the data section under the data heading DECAY-FLAG. If the flag may be omitted, its parentheses are also omitted.

Nuclide field. A nuclide code.

Half-life field. The half-life of the nuclide specified, coded as a floating-point number, followed by a unit code with the dimensions of TIME.

Radiation field. Consists of three subfields: (type of radiation, energy, abundance). This field may be omitted, or repeated (each radiation field being separated by a comma). The absence of any subfield is indicated by a comma; trailing commas are not included.

SF1. Type-of-radiation. A code from Dictionary 13. Where two or more different decay modes are possible and are not distinguished in the measurement, two or more codes are given; each separated by a slash. (See Example b, following).

SF2. Energy. The energy of the radiation in keV, coded as a floating-point number. In the case of two or more unresolved decays, two or more energies, or a lower and upper energy limit, are given, each separated by a slash. (See Example e).

SF3. Abundance. The abundance of the observed per decay, coded as a floating-point number.

Examples
  a)DECAY-DATA (60-ND-140,3.3D) (radiation field omitted)
b)DECAY-DATA (59-PR-140,,B+/EC,,0.500) (half-life and decay energy omitted)
c)DECAY-DATA (25-MN-50-G,0.286SEC,B+,6610.) (abundance omitted)
d)DECAY-DATA ((1.)60-ND-138,5.04HR,DG,328.,0.065) (decay flag, all fields present)
e)DECAY-DATA (60-ND-139-M,5.5HR,DG,708./738.,0.64) (the abundance given is the total abundance of both g rays)
f)DECAY-DATA(60-ND-139-G,30.0MIN,B+,,0.257,  
 DG,405.,0.055) 
 (60-ND-139-M,5.5HR, DG,738.,0.37, 
 DG,982.,0.29,  
 DG,708.,0.27, 
 DG,403.,0.03,  
 B+,,0.006) 

DECAY-MON.   Gives the decay data assumed by the author for any nuclide occurring in the monitor reaction used. The coding rules are the same as those for DECAY-DATA, except that there is no flag field.

DETECTOR.   Gives information about the detector(s) used in the experiment. Codes are found in Dictionary 22. If the code COINC is used, then the codes for the detectors used in coincidence follow within the same parenthesis;
Example:DETECTOR (COINC,NAICR,NAICR)

EMS-SEC.   Gives information about secondary squared effective mass of a particle or particle system, and to define secondary-mass fields given in the data table. The format of the coded information is: (heading, particle).

Heading Field contains the data heading or the root of the data heading to be defined.

Particle Field contains the particle or nuclide to which the data heading refers. The code is:

either a particle code from Dictionary 13.

or a nuclide code.

Example:EMS-SEC (EMS1,N)
(EMS2,P+D)

EN-SEC.   Gives information about secondary energies, and to define secondary-energy fields given in the data table. The format of the coded information is: (heading,particle).

Heading Field. Contains the data heading or the root of the data heading to be defined.

Particle Field. Contains the particle or nuclide to which the data heading refers. The code is:

either a particle code from Dictionary 13.

or a nuclide code.

Example:EN-SEC (E1,G)
(E2,N)
(E-EXC,3-LI-7)

ERR-ANALYS.   Explains the sources of uncertainties and the values given in the COMMON or DATA sections under data headings of the type ERR- or -ERR. The general code format is (heading,correlation factor) free text.

Heading Field. Contains the data heading or the root of the data heading to be defined.

Correlation Factor Field contains the correlation factor, coded as a floating point number.

Example:
  BIB
..
ERR-ANALYS (EN-ERR)followed by explanation of energy error
  (ERR-T)followed by explanation of total uncertainty
  (ERR-S)followed by explanation of statistical uncertainty

EXP-YEAR.   Defines the year in which the experiment was performed when it differs significantly from the data of the references given (e.g., classified data published years later).
Example: EXP-YEAR (1965)

FACILITY.   Defines the main apparatus used in the experiment. The facility code from Dictionary 18 may be followed by an institute code from Dictionary 3, which specifies the location of the facility.
Example: FACILITY (CHOPF,1USACOL)
(SPECC,1USABNL)

FLAG.   Provides information to specific lines in a data table. See also LEXFOR, Flags.
Example:
  BIB
:
FLAG(1.) Data averaged from 2 runs
(2.) Modified detector used at this energy
ENDBIB
:
DATA
ENDATAFLAG
KEVMBNO-DIM
1.2123.1.
2.3234.
3.4456.2.
ENDDATA

HALF-LIFE.   Gives information about half-life values and defines half-life fields given in the data table. The general coding format is: (heading,nuclide)

Example:HALF-LIFE(HL1,41-NB-94-G)
(HL2,41-NB-94-M)

HISTORY.   Documents the handling of an entry or subentry. The general format of the code is: (yyyymmddX), where yyyymmdd is the date (year,month,day) and X is a code from Dictionary 15.

Example:HISTORY(19940312C)
(19960711A) Data units corrected.

INC-SOURCE.   Gives information on the source of the incident particle beam used in the experiment. Codes are found in Dictionary 19.

Example: INC-SOURCE(POLNS,D-T)
INC-SOURCE(MPH=13-AL-27(N,A)11-NA-24)

INC-SPECT.   Provides free text information on the characteristics and resolution of the incident-projectile beam.

INSTITUTE.   Designates the laboratory, institute, or university at which the experiment was performed, or with which the authors are affiliated. Codes are given in Dictionary 3.

Examples:INSTITUTE(1USAGA, 1USALAS)
INSTITUTE(2FR SAC)

LEVEL-PROP.   Gives information on the spin and parity of excited states. The general format of the code is ((flag) nuclide, level identification, lever properties)

Flag. Coded as a fixed-point number that appears in the data section under the data heading LVL-FLAG. when the flag is omitted, its parentheses are also omitted.

Nuclide. Coded is a nuclide, except that the use of the extension G is optional.

Level identification. Identification of the level whose properties are specified, given as either a level energy or level number. If the field omitted, its separating comma is omitted.

Level Energy. The field identifier E-LVL= followed by the excited state energy in MeV, coded as a floating-point number which also appears in the data section under the data heading E-LVL.

Level Number. The field identifier LVL-NUMB= followed by the level number of the excited state, coded as a fixed-point number which also appears in the data section under the data heading LVL-NUMB.

Level properties. Properties for the excited state, each preceded by a subfield identification. At least one of the fields must be present. If the field is omitted, its separating comma is omitted.

Spin. The field identifier SPIN=, followed by the level spin coded as a floating point number. For an uncertain spin assignment, two or more spins may be given, each separated by a slash.

Parity. The field identifier PARITY=, followed by the level parity, coded as e.g., +1. or -1.

Examples:
  LEVEL-PROP(82-PB-206,E-LVL=0.,SPIN=0./1.,PARITY=+1.)
(82-PB-206,E-LVL-1.34,SPIN+3.,PARITY=+1.)
LEVEL-PROP((1.)82-PB-206,,SPIN=0./1.,PARITY=+1.)
((2.)82-PB-206,,SPIN=3.,PARITY=+1.)
LEVEL-PROP(82-PB-207,LVL-NUMB=2.,SPIN=1.5,PARITY=-1)

METHOD.   Describes the experimental technique(s) employed in the experiment. Codes are found in Dictionary 21.

Example:METHOD(RCHEM) Radiochemical separation

MISC-COL.   Defines fields in the COMMON or DATA sections headed by MISC and it derivatives.

Example:MISC-COL(MISC1) Free text describing 1st miscellaneous field
(MISC2) Free text describing 2nd miscellaneous field

MOM-SEC.   Gives information about secondary linear momentum, and defines secondary-momentum fields given in the data table. The general code format is: (heading,particle)

Heading Field: the data heading or root of the data heading to be defined.

Particle Field: the particle or nuclide to which the data heading refers. The code is:

either a particle code from Dictionary 13.

or a nuclide code.

Example:MOM-SEC(MOM-SEC1,26-FE-56)
(MOM-SEC2,26-FE-57)

MONITOR.   Gives information about the standard reference data (standard, monitor) used in the experiment and defines information coded in the COMMON and DATA sections under the data heading MONIT, etc. The general coding format is ((heading) reaction)

Heading Field. Contains the data heading of the field in which the monitor value is given. If the heading is omitted, its parenthesis is omitted.

Reaction Field. The coding rules are identical to those for REACTION, except that subfields 5 to 9 may be omitted if the reaction is known.

Example:
  REACTION1
2
(AAAAA)
(BBBBB)
 
MONITOR1
2
(CCCCC)
(DDDDD)
 
:
DATA
EN DATA1 DATA2MONIT1MONIT2
:

MONIT-REF.   Gives information about the source reference for the standard (or monitor) data used in the experiment.

The general code format is ((heading)subaccession#,author,reference)

Heading Field: Data heading of the field in which the standard value is given. If the heading is omitted, its parentheses are also omitted.

Subaccession Number Field: Subaccession number for the monitor data, if the data is given in an EXFOR entry. Cnnnn001 refers to the entire entry; Cnnnn000 refers to a yet unknown subentry.

Author Field: The first author, followed by "+" when more than one author exists.

Reference Field: May contain up to 6 subfields, coded as under REFERENCE.

Example:
 MONIT-REF((MONIT1)BOO17005,J.GOSHAL,J,PR,80,939,1950)
((MONIT2),A.G.PANONTIN+,J,JIN,30,2017,1968)

PART-DET. Gives information about the particles detected directly in the experiment. Particles detected in a standard/monitor reaction are not coded under this keyword. The code is either a code from Dictionary 13, or, for particles heavier than a particles, a nuclide code. Particles detected pertaining to different reaction units within a reaction combination are coded on separate records in the same order as the corresponding reaction units.

Example:PART-DET(A)
 PART-DET(3-LI-6)

RAD-DET.   Gives information about the decay radiations (or particles) and nuclides observed in the reaction measured. The general format of the code is ((flag)nuclide, radiation).

Flag is a fixed-point number which appears in the data section under the data heading DECAY-FLAG. If the field is omitted, its parentheses are also omitted.

Nuclide contains a nuclide code.

Radiation contains one or more codes from Dictionary 33, each separated by a comma.

Examples:
  RAD-DET(96-CM-240,A)
RAD-DET(25-MN-52-M,DG,B+)
RAD-DET(48-CD-115-G,B-)
(49-IN-115-M,DG)
RAD-DET((1.)48-CD-115-G,B-)
((2.)49-IN-115-M,DG)

REACTION.   Specifies the data presented in the DATA section in fields headed by DATA. The general format of the code is (reaction, quantity, data-type).

Reaction field. The reaction field consists of 4 subfields.

SF1. Target nucleus. Contains either:

  • a nuclide code.
    A = 0 denotes natural isotopic abundance.
  • a compound code.
  • a variable nucleus code ELEM and or MASS
Example:(ELEM/MASS(0,B-),,PN)

SF2. Incident projectile. Contains one of the following:

  • a particle code from Dictionary 28.
  • for particles heavier than an a, a nuclide code.

SF3. Process. Contains one of the following:

  • a process code from Dictionary 30, e.g., TOT.
  • a particle code from Dictionary 29 which may be preceded by a multiplicity factor, whose value may be 2 → 99. , e.g., 4A.
  • for particles heavier than a, a nuclide code.
    Examples:8-O-16
    8-O-16+8-O-16
  • combinations of a), b) and c), with the codes connected by '+'.
    Examples:HE3+8-0-16
    A+XN+YP

If SF5 contains the branch code UND (undefined), the particle codes given in SF3 represent only the sum of emitted nucleons, implying that the product nucleus coded in SF4 has been formed via different reaction channels. The code (DEF) in SF5 denotes that it is not evident from the publication whether the reaction channel is undefined or defined.

SF4. Reaction Product. In general, the heaviest of the products is defined as the reaction product (also called residual nucleus). In the case of two reaction products with equal mass, the one with the larger Z is considered as the heavier product. Exceptions or special cases are:

  • If SF5 contains the code SEQ, indicating that the sequence of several outgoing particles and/or processes coded in SF3 is meaningful, the nuclide to be coded in SF4 is the heaviest of the final products.
    Example:(5-B-10(N,A+T)2-HE-4,SEQ,SIG)
  • Where emission cross sections, production cross sections, product yields, etc., are given for specified nuclides, particles, or gammas, the product considered is defined as the reaction product (even if it is not the heaviest of several reaction products).
This subfield contains:
 either a blank,
 Example:(26-FE-56(N,EL),,WID)
or a nuclide code.
 Example:(51-SB-123(N,G)51-SB-124-M1+M2/T)
or, a variable nucleus codes:
 Example:(92-U-235(N,F)ELEM/MASS,CUM,FY)

Quantity consists of four subfields, each separated by a comma. All combinations of codes allowed in the quantity field are given in Dictionary 36.

SF5 Branch. Indicates a partial reaction, e.g., to one of several energy levels.

SF6 Parameter. Indicates the reaction parameter given, e.g., differential cross section.

SF7 Particle Considered. Indicates to which of several outgoing particles the quantity refers. Multiple codes, e.g., for the correlation between outgoing particles, all particles are separated by a slash.

SF8 Modifier. Contains information on the representation of the data, e.g., relative data.

Data Type Field. Indicates whether the data are experimental, theoretical, evaluated, etc. Codes are found in Dictionary 35.

SF9 Data Type.

Variable Nucleus. For certain processes, the data table may contain yield or production cross sections for several nuclei which are entered as variables in the data table. In this case, either SF1 or SF4 of the REACTION keyword contain one of the following codes:

ELEM- if the Z (charge number) of the nuclide is given in the data table.
MASS- if the A (mass number) of the nuclide is given in the data table.
ELEM/MASS- if the Z and A of the nuclide are given in the data table.

The nuclei are entered in the common data or data table as variables under the data headings ELEMENT and/or MASS with the units NO-DIM.

If the data headings ELEMENT and MASS are used, a third field with the data heading ISOMER is used when isomer states are specified:

  1. = ground state (used only if nuclide has also an isomeric state),
  2. = first metastable state (or the metastable state when only one is known),
  3. = second metastable state, etc.

Decay data for each entry under ELEMENT/MASS(ISOMER) and their related parent or daughter nuclides may be given in the usual way under the information-identifier keyword DECAY-DATA. Entries under the data headings ELEMENT/MASS(ISOMER) are linked to entries under DECAY-DATA (and RAD-DET, if present) by means of a decay flag.

Example:
 BIB
REACTION(..(..,F)ELEM/MASS,..)
ENDBIB
NOCOMMON
DATA
ENELEMMASSISOMERDATA
MEVNO-DIMNO-DIMNO-DIMB
..61.148.0...
..61.148.1...
..61.149. ..
..62.149. ..

Variable Number of Emitted Nucleons. Where mass and element distributions of product nuclei have been measured, the sum of outgoing neutrons and protons may be entered as variables in the data table. In this case SF3 of the REACTION keyword contains at least one of the following codes:

XN- variable number of neutrons given in the data table.
YP- variable number of protons given in the data table.

The numerical values of the multiplicity factors X and Y are entered in the data table under the data headings N-OUT and P-OUT, respectively.

Example:
  BIB
REACTION(:(:,XN+YP):)
..
ENDBIB
NOCOMMON
DATA
ENN-OUTP-OUTDATA
MEVNO-DIMNO-DIMB
..
..
..
ENDDATA

Reaction Combinations. For experimental data sets referring to complex combinations of materials and reactions, the code units defined in this section can be connected into a single machine-retrievable field, with appropriate separators and properly balanced parentheses. The complete reaction combination is enclosed in parentheses.

The following reaction combinations are defined:
  ((------)+(-----))Sum of 2 or more quantities (see LEXFOR, Sums).
((------)-(-----))Difference between 2 or more quantities.
((------)*(-----))Product of 2 or more quantities (see LEXFOR, Products).
((------)/(-----))Ratio of 2 or more quantities (see LEXFOR, Ratios).
((------)//(-----))Ratio of 2 quantities, where the numerator and denominator refer to different values for one or more independent variables (see LEXFOR, Ratios).
((------)=(-----))Tautologies (see LEXFOR, Tautologies for usage).

When a reaction combination contains the separator "//", the data table will contain at least one independent variable pair with the data heading extensions -NM and -DN.

Example:
  BIB
REACTION(((92-U-238(N,F)ELEM/MASS,CUM,FY,,FIS)/
(92-U-238(N,F)42-MO-99,CUM,FY,,FIS))//
((92-U-235(N,F)ELEM/MASS,CUM,FY,,MXW)/
(92-U-235(N,F)42-MO-99,CUM,FY,,MXW)))
RESULT(RVAL)
:
ENDBIB
COMMON
EN-DUM-NUMEN-DUM-DN
MEVEV
1.00.0253
ENDCOMMON
DATA
ELEMENTMASSDATA
..
ENDDATA

REFERENCE.   Gives information on references that contain information about the data coded. Other related references are not coded under this keyword (see REL-REF, MONIT-REF). The general coding format is (reference type, reference, date).

The format of the reference field is dependent on the reference type. The general format for each reference type follows.

Type of Reference = B or C; Books and Conferences.
General code format: (B or C,code,volume,(part),page(paper #),date). Codes from Dictionary 7.

Examples:
  (C,67KHAROV,,(56),196702)Kharkov Conference Proceedings, paper #56, February 1967.
(C,66WASH,1,456,196603)Washington Conference Proceedings, Volume 1, page 456, March 1966
(B,ABAGJAN,,123,1964)Book by Abagjan, page 123, published in 1964.

Type of Reference = J: Journals.
General code format is (J,code,volume,(issue #),page,date). Codes are from Dictionary 5.

Examples:
  (J,PR,104,1319,195612)Phys. Rev. Volume 104, page 1319, December 1956
(J,XYZ,5,(2),89,196602)Journals XYZ, Volume 5, issue #2, page 89, February 1966

Type of Reference = P or R or S; Reports.
General code format: (P or R or S,code-number,date). Codes from Dictionary 6.

Examples:
  (R,JINR-P-2713,196605)Dubna report, series P, number 2713, May 1966.
(P,WASH-1068,185,196603)WASH progress report number 1068, page 185, March 1966.

Type of Reference = T, or W; Thesis or Private Communication.
General code format: (W or T,author,page,date)

Examples:
  (W,BENZI,19661104)private communication from Benzi, November 4, 1966.
(T,ANONYMOUS,58,196802)thesis by Anonymous, page 58, February 1968.

REL-REF.   Gives information on references related to, but not directly pertaining to, the work coded. The general code format is: (code,subaccession#,author,reference).

Code: code from Dictionary 17.

Subaccession #: EXFOR subaccession number for the reference given, if it exists. Cnnnn001 refers to the entire entry Cnnnn. Cnnnn000 refers to a yet unassigned subentry within the entry Cnnnn.

Author: first author, coded as under AUTHOR, followed by + when more than one author exists.

Reference: coded as for REFERENCE.

Example:
 (C,B9999001,A.B.NAME+,J,XYZ,5,(2),90,197701) Critical remarks by A.B.Name, et al., in journal XYZ, volume 5, issue #2, p. 90, January 1977.

RESULT.   Describes commonly used quantities that are coded as REACTION combinations.

Example:
  REACTION((Z-S-A(N,F)ELEM/MASS,CUM,FY)/(Z-S-A(N,F)MASS,CHN,FY))
RESULT(FRCUM)

SAMPLE.   Used to give information on the structure, composition, shape, etc., of the measurement sample.

STATUS.   Givews information on the status of the data presented. Entered in one of the general code formats, or for cross reference to another data set, the general code format is: (code,subaccession#)

Code: code from Dictionary 16.

Subaccession# Field: cross-reference to an EXFOR subaccession number, see REL-REF.

Example:
  STATUS(SPSDD,10048009)- this subentry is superseded by subentry 10048009.

TITLE.   Gives the title for the work referenced.



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