This study was performed in the process of preparation of CKM proposal for PAC review in March 2001. The goal was to study kinematical suppression of Kpi2 background and acceptance of the signal. In proposal we would like to have 2 events out of 1M kpi2 to sneak into the signal region, and we wanted to verify that using Geant Monte-Carlo. This job was repeated several times, because different bugs/features were uncovered. Below is the summary of the studies.
| try# | date | ckmgeant version |
Code adjustments |
Improvements | samples |
|---|---|---|---|---|---|
| try1 | Feb 23 | v3_2 | none | First version with complete CKM geometry. BIVS has lead/scint structure. The DMS and RICH analysis codes are installed. Update geometry of UMS with larger chambers. | 100k kpinn 535k kpi2 |
| try2 | Mar 3 | v3_3 | none | Update KRICH so that it cuts off lower wavelengths. This improves angular resolution. Now have capability to use matrix elements in decays. Available decay matrix elements now include: K->e nu gamma K->mu nu gamma. Can now stop showering of particles in vetoes with SWIT 4 1 option. UMS analysis code is installed. | 100k kpinn 1M kpi2 |
| try3 | Mar 10 | v3_4 | none | KEAT's taken out of the vacuum and put at 2.6m separation. Vertex finding routine installed. KEAT's included in UMS pattern recognition and track fitting. Available decay matrix elements now include: K->pi nu nubar K->pi gamma gamma | 100k kpinn 100k kpi2 100k kmu2 |
| try4 | Mar 12 | v3_4 | none | 100k kpi2 | |
| try5 | Mar 16 | v3_5 | Available decay matrix elements now include: K->pi e+ e-, K->pi mu+ mu- Tag initial kaon so that it can have hadronic interactions and still be forced to decay within specified region. Dead beam region added to DMS chambers. Mylar entrance window for vacuum chamber. | 100k kpinn 100k kpi2 |
|
| try6 | Mar 16 | v3_5a | 100k kpinn 1M kpi2 |
||
| try7 | Mar 20 | v3_5a | 100k kpinn 1M kpi2 |
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| try8 | Mar 23 | v3_5a |
gukine.F ,
guout.F ,
gustep.F
speedup by taking out calls to BIVS and VVS
CKM_read_user.F , keatana.F Kaon track calculated using 2 KEAT stations bivs_geom.kumac Changed the tracking medium from air to vacuum for inside the BIVS. ckmgeom.F Changed liquid helium into gaseous helium (affected only KEAT) keat_geom.F , pwc_08_120_lrg.config Changed KEAT chamber separation to 320 cm |
100k kpinn 1M kpi2 |
|
| try9 | Mar 27 | v3_6 |
gukine.F ,
guout.F ,
gustep.F
speedup by taking out calls to BIVS and VVS
ums_geom.F UMS helium bags geomerty fixed (were 0 thikness tubes) |
BIVS now has vacuum in the interior. DMS straw tubes made of 'gaseous kapton'. KEAT stations separated to 3.2 m Kaon angle now calculated only from KEAT hits. | 100k kpinn 1M kpi2 |
| try10 | Apr 29 | v3_7 | gukine.F , guout.F , gustep.F speedup by taking out calls to BIVS and VVS |
Go back to original DMS straw construction. Set fixed 10
micron precision for step size calculation in GEANT.
GEANT now calculates tracking parameters automatically.
Various geometry fixes, mostly to magnetic fields, allow
this. Add 4 body decay modes:
pi+ pi- e+ nu (ubuf(1)=7) pi+ pi- mu+ nu (ubuf(1)=8) pi0 pi0 e+ nu (ubuf(1)=9) pi0 pi0 mu+ nu (ubuf(1)=10) pi0 mu+ nu gamma (ubuf(1)=11) pi0 e+ nu gamma (ubuf(1)=12) w/o matrix element Wire pitch in UMS fixed. Magnetic field kick correctly set to 99.8 MeV. Optimize VVS code. |
100k kpinn 1M kpi2 |