The database CS (Cross Sections) includes data on integral
properties of particles collisions and is a development and update of
the HERA(CERN) compilations [1]. One can find in the CS database
the mostly complete set of formaly evaluated data on the topics:
The collection of the CS data base and formal evaluation of data have been made in several stages: merging of 1987 HERA(CERN) compilations translated on PPDL (Particle Physics Data Language) with data from old UCRL and LBL compilations.
In all cases the data were checked with original publications before loading to the CS database. Practically all experimental data points presented in CS data base are repeatedly checked by comparing stored data with data in the original publications.
Where it was possible the preliminary data were marked with special mark that makes it easy to separate them from final results. Another special key marks the data obtained in not full phase space and/or model dependent data.
The PPDL language and highly developed program tools give a possibility to establish a strong control of reaction description and, as a result, reduces an amount of wrong descriptors and, in many cases, rejects errors arosing from misprints in journals.
CS data compilation now updated regularly by data from ReacData (RD)
data base [3,5].
Basic unit of the CS data base under BDMS is a record - a set of data elements connected by hierarchical relations. Each record contains the data belonging to one reaction (RE), one observable (YN) and extracted from one publication (R). Record schema is as follows:
Biblio Reaction Data Experimental Service
graphy Descriptors Points Conditions Descriptors
*==============================*=========*==================*======*
| ||| | | | | | | | | | | | | | | | | | | | | |
SC||| | RE| | | | | | | YN | | KIN | |SIG | |DEN | cr
||| | | | | | | |MODE | | | | | | |
R|| | REC| | | | | point | CORR| SB | DCH
|| | | | | | | / | | \ sys | |
D| | BP'| | |MULT btm | | y / \ COND |
| | | | | | | | csys \ ___ds__
TY| TP'|brv PLAB | | sys-err / | \
| | | ysis DSA DSR dcc
RR FSP' ECM
Key data elements (DE) are in upper case, (') marks the virtual DE,
which are created by the program from other data. To output the information stored in compilation a user can utilize both standard facilities of the BDMS (commands PRINT, DUMP, LIST) and those supplied by the applied programs (command DOCUMENT). Using the command DOCUMENT one can get several types of output specified by MODD,< number> command, which must be issued before DOCUMENT command.
The output by
A part of the listing relating to a single reaction has two lines: the first one specifies the parameter as follows: the reaction code, the masses of beam and target particles, the reaction threshold for the momentum in laboratory system and for the center of mass system energy (all in GeV) ,multiplicity in the final state and the data element YN. The second line specifies the number of points for a given reaction in the current set.
In addition to the above output contains also the lines describing the experimental points. These lines follow one describing the reaction. The experimental points are ordered according to the beam momentum.
One line corresponds to one experimental point and contains the following information: the mean value, the right and left boundaries of momenta spectrum, the same parameters for the energy in c.m.s. (all in GeV), the YN value, the negative and positive errors, warning comment, systematical errors in percents, SC of the record and reference to the publication.
The warning comment is the symbol "W". It appears in the next cases:
In the case when KIN = RDB; or KIN = CALC; the warning comment equals "R" and "C" respectivelly. The output according MODD,2 is acceptable by the system ATLAS [8].
gives the fullest information about the record. As a kinematical variables PLAB and ECM are used. The value of YN is corrected for the current PDG branching ratio value from BRV.
If authors have corrected the value of YN on branching and this fact is marked by encoder in the data element SIG, then the line
CORRECTED BY AUTHORS
appears in the output for given record.
If for some reasons the correction haven't been made then the line
UNCORRECTED
appears in the record.
The type of output according to MODD,4 is equivalent to the MODD,3 except the value of YN not corrected for current value of branching ratio. This mode is convenient in checking data.
If SET that have been formed by the user contains the information belonging to one reaction only, it is strongly recommended to use outputs MODD,5 and MODD,6 instead of MODD,1 and MODD,2 respectively. They are complitely identical but are at least ten times faster.
Technical format of output to be used in the procedure CSBOOK. Equivalent to MODD,6 with additional outputted lines that describes the decay brackets of decaying particles.
Produces the output in the format of CERN-HERA compilations.If the particle(s) in final state have been observed in a particular decay mode(s) it will produce two lines for a single entry - one with corrected cross section and another with uncorrected.
Produces the output equivalent to one of ReacData data base in the MODD,2 grouped according to reactions.
Equivalent to MODD,9. Should be used if the set to be output contains the records with unique reaction. Is at least an order faster than MODD,9
Equivalent to MODD,2. Supresses the output of PLAB value and gives the overall systematic and individual errors as separate entries.
Equivalent to MODD,11. Should be used when the selected set contains the records with the same reaction.
An access to the data base CS in the VMS media is given by PPDS macro-command. A powerfull internal help on the BDMS system (commands: ?, ??, ?< command>) and on the data base itself (commands: HELPBASE, FDT, INDEX, GUIDE) give a possibility to become familiar with BDMS system and data base in a short time.
Describing compilation contains now about 21500 records, that corresponds to about 45000 experimental points. All records except for very little part were checked by COMPAS group (IHEP). All these record have data element SB.
In the future we plan to maintain the data base with the help of PPDS's data bases DataGuide (DG) and ReacData (RD) with additional checking of the records against publications whenever it is possible.
We plan also future development of the data base in some directions: rejection of errors in data presentation, construction of "the basal data sets" with the help of expert evaluations published elsewhere and stored in the data elements DS, DSA, DSR, DSC, new possibilities in data manipulation.
All criticism on quality of data base, proposals on future development will be accepted with pleasure and used in our work.