LEAR Crystal Barrel Experiment, PS197 User Guide for CBDROP A
Contents
1. the default is 1 00 A possible example setup of CBDROP is given in the following snipit of the USINIT routine This is used to select two prong events SUBROUTINE USINIT CDE USDCUT CDE TCCVRX CALL USDINI NTRKUS 2 EGAMUS 20 0 It also seems necessary to modify the default tracking errors The following values seem reasonable for the November 90 data ALPHUS 2 33 PSIFUS 1 20 TGLMUS 1 20 AFACUS 1 0725 XENEUS 1 30 XTHEUS 1 30 XPHIUS 1 30 User Guide for CBDROP 5 3 2 Event Processing In your USER routine you need to call the CBDROP subroutine You then need to make a decision on whether to keep or reject the event based on what CBDROP returns It is also necessary that you provide sufficient working space for CBDROP The following code snippet indicates how to setup and call cbdrop for dropping a maximum of NTRY 2 neutral PED s SUBROUTINE USER CDE USDCUT CDE USPMOM INTEGER NTRY PARAMETER NTRY 2 INTEGER NKEEP 0 NTRY IKEEP 20 2 2 0 NTRY INTEGER NDROP 0 NTRY IDROP 20 2 2 0 NTRY INTEGER INDX REAL CLEV 0 NTRY CLEV2 0 NTRY IERR 0 CALL CBDROP NTRY INDX NDROP NKEEP IDROP IKEEP CLEV amp CLEV2 IERR NLOW IF IERR NE 0 RETURN The variable IERR is an error status word that gives some indication of why the fit failed Only events with IERR equal to 0 should be accepted Other possible values with their meanings are 10 072. 06 05 04 03 02 01 00 01 03 05 07 Passed NTRY is negative Event fails smart mode criteria see INTLUS More than 20 particles in the event More than 40 particles in TTKS bank Photon Loading fails Track Mask is wrong event does not satisfy all conditions required in MASKUS Track load fails Number of tracks was not NTRKUS Successful fit of data Global tracking bank does not exist Chisqure from the kinematic fit is larger than 1 000 000 Kinematic fit failed to converge in 10 iterations Kinematic fit tried to invert singular matrix 6 User Guide for CBDROP Assuming that IERR is zero then NLOW is the number of photons in the TTKS bank that were simply ignored as their energy was too low You will now need to address the data The variable INDX indicates which drop combination had the largest confidence level The best confidence level is CLEV INDX the number of photons dropped in the best case is NDROP INDX and the number kept is NKEEP INDX A list of the n kept photons TTKS id is given as IKEEP 1 N 2 1 INDX while their TBTK id are given as IKEEP 1 N 1 1 INDX Similar lists of the dropped photons are given in the IDROP 1 N 2 1 1 INDX array Also at this point the 4 C kinematically fit variables for the best combination areavailable in the USPMOM common block see section 22 In addition to the previous information the same information is available for the best of each of
3. event configuration This code is based on the analysis procedure developed by B Schmid for her analsysis of NTNTNN CBDROP is the generalization of this method in a documented package form and and is presently being used by D Urner for ntn 7 n y and C A Meyer for rtn r n n Any questions comments or complaints should sent to cmeyer vogon physik unizh ch 2 Installation CBDROP is distributed as a CMzZ file The code is slightly machine dependent but the normal Crystal Barrel machine flags are used The CMz file can be found in the following places e CB DECSTATIONS cboff pro cmz cbdrop cmz e e mail cmeyer ernest phys cmu edu You can get the CMZ using binary FTP Then create a source subdirectory under the account containing CBDROP CMZ You can now use the automatic installation procedure which on a Unix platform is cmz install cbdrop src directory options While under VMS this is CMZ INSTALL CBDROP src directory options The allowed options are e ALL Create source code a library and the manual e LIB Create the library e SOURCE Create the compiled source code e TEXT Create the manual 2 User Guide for CBDROP 3 How To Use CBDROP To use the CBDROP code one must first initialize the package Then for every event for which there is a chance that dropping photons can help one should call the CBDROP code Even though CBDROP will check to make sure that the event is consistent with your requirements befor
4. section for a description e LEGAUS Set to TRUE if CBDROP should place a cut on the PED energy e LTAXI2 Set to TRUE if CBDROP should respect the results of TAXI e LDOLBY Set to TRUE if CBDROP should respect the results of DOLBY e LSMART Set to TRUE if CBDROP should respect the results of SMART e INTLUS If set larger than zero smart mode is activated In smart mode CBDROP will not fit any combinations in which the number of photons is smaller than NGMNUS It will also make sure that given the allowed number of drops that the event could come into the range NGMNUS to NGMXUS see section 27 4 2 USPALL The USPALL keep is a common block used to speed up loading of data for the kinematic fit Tt contains entries for all particles which could possibly be used in the event In order to access these particles one needs to use the IGALUS values as a pointer to where the data are stored they are stored in the index corresponding to their global tracking number DO ITRK 1 NALLUS I IGALUS ITRK DO K 1 3 P K PALLUS K I END DO END DO The variables in this common block are given as follows REAL PALLUS 3 40 CVALUS 3 3 40 CHALUS 40 MSALUS 40 INTEGER IGALUS 40 LGALUS 40 EDGEUS 40 NALLUS INTEGER NBADUS IBADUS 40 COMMON USPALL PALLUS CVALUS CHALUS MSALUS amp IGALUS LGALUS EDGEUS NALLUS amp NBADUS IBADUS SAVE USPALL e PALLUS Initial momentum vectors of all particles e
5. up in the usual method CDE Common block name 8 User Guide for CBDROP 4 1 USDCUT The USDCUT keep is a common block used for steering the drop job Not all variables in this common are used by CBDROP but they are present due to historical reasons They can be used by the USER to steer the running of CBDROP REAL EGAMUS ECENUS EBALUS PBALUS ESMCUS PSMCUS REAL VSHFUS 3 INTEGER NDRPUS NGMNUS NGMXUS NGAMUS NTRKUS LONGUS INTEGER IVRTUS MASKUS ISHFUS IGTRAK INTLUS LOGICAL LEDGUS LCENUS LEGAUS LTAXI2 LDOLBY LSMART COMMON USDCUT EGAMUS ECENUS EBALUS PBALUS ESMCUS PSMCUS amp VSHFUS NDRPUS NGMNUS NGMXUS NGAMUS NTRKUS amp LONGUS IVRTUS MASKUS ISHFUS IGTRAK LEDGUS amp LCENUS LEGAUS LTAXI2 LDOLBY LSMART INTLUS SAVE USDCUT e EGAMUS A real variable which defines the minimum allowed energy for a photon See the initialization section for a description e ECENUS A real variable which defines the minimum energy in the central crystal of a ped e EBALUS Is the energy constraint used in the 4 C fit e PBALUS Is the p constraint used in the 4 C fit You must guarantee that EBALUS and PBALUS are consistent e ESMCUS Used to preselect fit combinations based on the total energy See section e PSCMUS Used to preselect fit combinations based on the momentum balance See section e VSHFUS Used to define an alternate fixed vertex for all events This is onl
6. 0 I 1 NDROP INDX JIDROP I IDROP I 2 1 INDX 300 CONTINUE It is also possible for the user to prevent individual unmatched PED s from being used by CBDROP The variables NBADUS and IBADUS in the PALLUS common block have been provided for this purpose In order to implement this add the following snipit of code to you USER routine before calling CBDROP CDE USPALUS NBADUS 0 User Guide for CBDROP 7 Now you need to decide which PED s you do not want to use Assuming that you decide that TTKS particles 4 7 and 12 are not wanted then NBADUS 3 IBADUS 1 4 IBADUS 2 7 IBADUS 3 12 CALL CBDROP It is very important that you reset the value NBADUS to zero at the start of every event Because of the nature of this cut CBDROP has no sensible method of resetting NBADUS at the start of a new event If you did not change NBADUS then the above three PED s would be disabled on every event 3 3 Event Processing in Smart Mode If you are looking for a specific final state not several simultaneously and you are planning to use CBKFIT in addition to CBDROP then you probably want to consider using the smart mode of CBDROP If you run in this mode you must specify the number of photons allowed in the final state CBDROP will then vary its dropping rules to try to maximize the number of events in your configuration It will also skip over events which have no chance of fullfilling your specific final state criter
7. AM 22 GAMM 0 0000 IPIQ 211 PIQM 139 5673 IPIO 111 PIOM 134 9739 IkQ 321 KQM 493 646 IKO 311 KOM 497 671 IETA 221 ETAM 548 4 IOMEG 223 OMEGM 781 95 IETAP 331 ETAPM 957 50 IPHI 333 PHIM 1019 412 IRHQ 213 RHQM 768 3 IRHO 113 RHOM 768 3 IPROT 2212 PROTM 938 27231 User Guide for CBDROP 11 4 4 USPMOM The USPMOM keep is a common block used to return the kinematic fit results Upon completion of CBDROP the variables will be loaded with the results for the best overall 4 C fit These may or may not be the desired results but are available as a by product of the CBDROP call without any extra effort All momentum vectors are in Cartesian coordinates pz Py Dz REAL PINIUS 3 20 PFITUS 3 20 DELPUS 3 20 CHSQUS 20 REAL CVINUS 3 3 20 CVFTUS 3 3 20 CHRGUS 20 MASSUS 20 INTEGER IGIDUS 20 NPRTUS COMMON USPMOM PINIUS PFITUS DELPUS CHSGUS CVINUS CVFTUS amp CHRGUS MASSUS IGIDUS NPRTUS SAVE USPMOM e PINIUS Initial momentum vectors of the NPRTUS particles e PFITUS Fit momentum vectors of the NPRTUS particles e DELPUS Change in momentum vectors initial minus fit e CHSQUS Contribution to chisquare of each track e CVINUS Initial covariance matrix of each particle e CVFTUS Fit covariance matrix of each partcile e CHRGUS Charge of the each particles e MASSUS Mass of the each particles e IGIDUS The number of this particle in the TTKS data ban
8. CB Note 191 LEAR Crystal Barrel Experiment PS197 User Guide for CBDROP A Charged Splitoff Supression Package Curtis A Meyer Universit t Z rich 30 June 1992 updated on 29 March 1995 SSSR Contents User Guide for CBDROP 1 1 Introduction The CBDROP code is designed to try and enhance data samples in the mixed charged and neutral environment In these mixed channels many charged particles will produce more than one energy deposit in the barrel However for global tracking to make any sense it can attach at most one PED to a given track The purpose of CBDROP is to attempt to figure out which if any additional PED s should also be considered as charged split offs The method is based on a fast 4 C kinematic fit to momentum and energy balance The event is initially given to the fitter as it stands This leads to a confidence level Po in which none of the neutral PED s are considered as charged split offs drop 0 Next for n neutral PED s in the event n fits are performed each dropping a different neutral PED The drop combination that yields the maximum confidence level P is retained as the best drop 1 combination Additionally every possible pair of neutral PED s can be dropped yielding a best drop 2 confidence level P gt This can be continued to yield a drop 3 up to a drop n If one allows at most m drops typically one per charged track then the maximum of Pp Pi Pm is retained as the true
9. CVALUS Initial covariance matrix of each particle e CHALUS Charge of the each particles e MSALUS Mass of the each particles e IGALUS The number of this particle in the TTKS data bank 10 User Guide for CBDROP e LGALUS Does the particle pass energy cuts O yes e EDGEUS Edge Crystal Test O not edge crystal e NALLUS Number of stored particles e NBADUS Number of PED s the user wants to disable e IBADUS List of NBADUS disables PED s 4 3 USPART The USPART keep is not actually a common block but rather data on many different particles The following particles are presently included INTEGER INTEGER PARAMETER PARAMETER PARAMETER PARAMETER PARAMETER PARAMETER PARAMETER PARAMETER REAL REAL PARAMETER PARAMETER PARAMETER PARAMETER PARAMETER PARAMETER PARAMETER Particle photon pion pion 0 kaon kaon 0 eta 548 omega 782 eta 958 phi 1020 rho rho 0 proton IGAM IPIQ IPIO IKO IKO IETA IOMEG IETAP IPHI IRHQ IRHO IPROT IGAM 22 IPIO 111 IPIQ 211 IKO 321 IKO 311 IETA 221 I0MEG 223 IETAP 331 IPHI 333 IRHQ 213 IRHO 113 IPROT 2212 GAMM PIOM PIQM KOM KOM ETAM OMEGM ETAPM PHIM RHQM RHOM PROTM GAMM 0 0000 PIOM 134 9739 PIQM 139 5673 KOM 497 671 KQM 493 646 ETAM 548 8 OMEGM 781 95 ETAPM 957 50 PHIM 1019 412 RHQM 768 3 gt RHOM 768 3 PROTM 938 27231 Code Mass IG
10. S is a REAL variable which defines the z momentum constraint applied in the 4 C kinematic fit The default value is zero in units of MeV c No check is made to assure that EBALUS and PBALUS are internally consistent e ESMCUS is a real variable which defines a cut applied to the unfit energy balance before a 4 C fit is performed If Esum EBALUS gt ESMCUS then the Confidence Level is set to 0 and no fit is made The default is 10000 0 which is essentially no cut e PSMCUS isa REAL variable which defines a cut applied to the momentum balance before a 4 C fit is performed If Psum PBALUS gt PSMCUS then the Confidence Level is set to 0 and no fit is made The default is 10000 0 which is essentially no cut e VSHFUS is a REAL array of dimension 3 In conjunction with ISHFUS the user can move the photon vertex from the one defined in the data base to vSHFUS The default is 0 0 0 and the option is turned off e LEGAUS is a LOGICAL variable that when set only accepts PEDS whose energy is larger than EGAMUS e LCENUS is a LOGICAL variable that when set only accepts PEDS whose central energy is larger than ECENUS The default value of LCENUS is FALSE e LTAXI2 is a logical that when set forces CBDROP to repsepct the spilt off decision taken by TAXI2 Its default value is TRUE User Guide for CBDROP 3 e LDOLBY is a logical that when set forces CBDROP to respect the split off decision taken by DOLBY Its default val
11. e running it is still faster to prefilter the events If you are looking for final states such as 7 7 6y then it makes no senese to call CBDROP when the event has more than 2 tracks at the vertex or when the total number of neutral PED s is smaller than 6 3 1 Initialization In order to initialize the CBDROP code it is necessary to call the USDINI routine from your USINIT routine This will define a default configuration for CBDROP This default configuration can then be modified to suit your own needs see the example code at the end of this section To modify the default configuration you need to include the USDCUT common in your USINIT code see below You can then modify the following variables Note that these are only used to steer the CBDROP code their values will never be changed by the CBDROP routine e EGAMUS is a REAL variable which defines the minimum energy of a photon default is zero The photon energy is taken from word 15 of the TTKS global tracking bank The default will accept all neutral particles in the TTKS bank as photons Setting a different value will take only those particles whose energy is larger than EGAMUS as photons e ECENUS is a REAL variable which defines the minimun energy in the central crystal of a PED It has a defualt value of zero e EBALUS is a REAL variable which defines the energy constraint applied in the 4 C kinematic fit The default value is 2 proton masses in units of MeV e PBALU
12. ia e If the number of photons in the event is smaller than the number you requested the event will be skipped In this case an error code of 7 is returned by CBDROP e f the number of photons minus the maximum to drop is larger than the number of requested the event will be skipped In this case an error code of 7 is returned by CBDROP e CBDROP will only drop sufficient photons to exactly satisfy your request NGMNUS If you ask for 6 allow CBDROP to drop up to 2 and the event has 7 potoential photons then on this event CBDROP will not try the drop 0 and drop 2 combinations only the drop 1 will be performed To set up this mode you must specify the number of photons you want and turn on the mode This is done in USINIT after your call to USDINI In the case of 6 photons the following code must be used NGMNUS 6 NGMXUS 6 INTLUS 1 After this is done the code will try to maximize the number of events with exactly six photons This can be dangerous as it not only increases the true signal but also the background For this reason it is strongly reccomended that this mode be used only in conjunction with CBKFIT i e the 7 C fit to 37 s If this is done correctly it can give an extra 20 30 data with minimal extra background If you do not plan to use CBKFIT with extra constraints then you should be rather wary of using this mode 4 Full Common Block Description All of the following common blocks can be picked
13. k e NPRTUS Number of particles in the fit
14. n e NGMNUS used to set a lower bound on the number of photons in the event See INTLUS the default is zero 4 User Guide for CBDROP e NGMXUS used to set an upper bound on the number of photons in the event See INTLUS the default is zero It may also be necessary to modify the errors related to charged tracks In order to do this is in a consitent manner the common block TCCVRX has been provided By setting scale factors here which scale the error not the error squared the TCHLDD S routines will set reasonable errors for the charged tracks One should note that when tracks are taken from either the TTKS or TCTR banks CBDROP realizes that all the errors in need to be doubled to compensate for the fact that one is not fitting at the vertex This is done automatically e ALPHUS The factor by which the error is a is scaled The default is 1 00 e TGLMUS The factor by which the error in tan A is scaled The default is 1 00 e PSIFUS The factor by which the error in w is scaled The default is 1 00 Note there is an automatic factor of two in this factor internal in CBDROP Do not set this value to 2 to get the vertex correction described above e AFACUS Allows one to scale the transverse momentum by this factor The deafult is 1 00 e XENEUS Scale factor applied to the error in the E The default is 1 00 e XTHEUS Scale factor applied to the error in 6 the default is 1 00 e XPHIUS Scale factor applied to the error in
15. t 2 At least one track is poorly fit Bit 3 At least one track starts outside layer 5 Bit 4 The vertex convergence is poor x Mask 13 01101 gt Q_sum E_code Start layer Mask 15 01111 gt Q_sum Length E_code Start_layer e ISHFUS is an INTEGER variable If set to zero default no vertex corrections to the photons are made If set to one then the vertex is corrected to VSHFUS 1 3 If set to two then the vertex is even event corrected to the charged vertex e IGTRAK is an INTEGER variable For charged particles the default is to assume that everything is a pion IGTRAK 0 However if IGTRAK is set to one 1 the the particle ID kaon or pion is taken from the global tracking bank This is determined by looking at the words 28 and 29 and choosing which is larger Setting IGTRAK 2 will force all charged tracks to be identified as kaons Note that this variable can only be used for IvRTUS of 0 e INTLUS If set to a postive value default is zero then the so called smart mode is activated In this mode the variables NGMNUS and NGMXUS are used to define the maximum and minimum desired photons If the number of potential photons is smaller than NGMNUS or the number minus the maximum allowed drop is larger than NGMXUS then the events will not be fit Also the actual maximum number dropped may not be the number passed In this mode the routine will perform no fits with fewer than NGMNUS photons see sectio
16. the NTRY drops These data are addressed by simply replacing INDX in the previous section with the number of dropped photons e g 0 1 NTRY Finally if this is not preverse enough the second best solution for each of the NTRY drop com bunations are also available The confidence levels for these are stored in the CLEV2 array The list of kept photons for the second best combination of dropping m are available as IKEEP 1 N 2 1 2 M while the dropped list is similarly IDROP 1 N 2 1 2 M Assuming that you are willing to believe that the best combination as chosen by CBDROP is really the true combination the following snippet of code shows how to extract the data First you might want to make a cut on the number of photons in the event IF NKEEP INDX LT NGMNUS OR amp NKEEP INDX GT NGMXUS RETURN Now make sure that the confidence level is reasonable Here we reject events with a confidence level smaller than 1 IF CLEV INDX LT 0 01 RETURN Now it would be useful save the global tracking numbers of the kept particles charged plus neutral for possible use by CBKFIT We will store these in a varaible LISTUS Note that rather than the IKEEP list of photons I am taking this list out of the USPMOM common block DO 100 I 1 NPRTUS LISTUS I IGIDUS I 100 CONTINUE One could also get the list of kept and dropped photons as follows DO 200 I 1 NKEEP INDX JIKEEP I IKEEP 1 2 1 INDX 200 CONTINUE DO 30
17. ue is TRUE e LSMART is a logical that when set TRUE forces CBDROP to respect the split off decision taken by SMART Only SMART code 1 PEDS are rejected This variable has a default value of FALSE e NTRKUS is an INTEGER variable which defines the number of charged tracks allowed in the event The default is zero so you will certainly need to change this Events without exactly NTRKUS tracks attached to the primary vertex are rejected All tracks are assumed to be pions unless you modify IGTRAK e LONGUS is an INTEGER to define the minimum length of each track All of the NTRKUS tracks must span at least LONGUS layers The default is ten Note that for a track to be connected to a vertex it must already start no later than layer five e IVRTUS is an INTEGER variable to select if the track data are taken from the TTKS TCTR or TCVT data banks The default value of zero will select data from the TTKS data bank Setting this to 1 will select data from the TCTR data bank and 2 will select data from the TCVT banks Note that if you choose option one or two then ALL charged particles will always be treated as pions Only with option zero can you choose to accept the global tracking identification see IGTRAK e MASKUS is an INTEGER bit mask for rejecting charged tracks at the vertex the default is 15 where the meaning is in the following table Bit 0 Charge does not sum to zero Bit 1 All tracks are not long LONGUS Bi
18. y applied when ISHFUS is set to 1 e NDRPUS Maximum number of PEDS to drop Not used by the package but made available for private use e NGMNUS The minimum number of photons desired Only used in smart mode see section e NGMXUS The maximum number of photons desired Only used in smart mode see section e NGAMUS The number of photons in the present event Filled by the package upon completion e NTRKUS The number of tracks at the vertex See Section for a description If the event does not have NTRKUS tracks at the vertex it is not fit e LONGUS The minimum track length See section for usage All NTRKUS tracks must have a length of at least LONGUS e IVRTUS Take track data from TTKS 0 TCTR 1 or TCVX 2 See section for usage e MASKUS A track quality mask see sectio for a description and usage e ISHFUS Used to modify the vertex for photons If set to 0 then no modification is done If set to 1 all events are shifted to VSHFUS and if set to 2 all events are shifted to the charged vertex User Guide for CBDROP 9 e IGTRAK If set to one then use the global tracking particle type for charged particles pion or kaon When left zero all charged particles are assumed to be pions If set to two all particles are assumed to be kaons e LEDGUS Reject Events with edge PEDS This cut must be applied by the user The variable is not used in the package e LCENUS Use central crystal energy See
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