1. Summary of fiducial volume test at KEK
K. Okumura, G. Mitsuka
29-August-2005
2km video meeting

2. Schedule setup measurement
planned schedule
preparation
actual schedule
setup
measurement
restore
fiducial experiment was carried out from 4-July until 12-August
total schedule was extended about 1 week from initial plan due to delay of setup
experiment was finished without any serious accident

3. Install procedure of grid PMTs1 2
lower water level by 2m
remove black sheet around entrance
open tank
float air boat on water
put one person on boat
feed metal wire through top frame
hang PMT support frame by wire 3 4
close tank
re-fill water (this will take a few days)
insert CRP
start CRP run
same procedure for restoration
sunk PMT and support frame into water

4. grid PMT and support frame
R9869ASSY
2-inch with vessel
positive HV
water proof
support frame
size 120x120cm
3x3 PMTs arranged, 50cm spacing

5. Open 1kton tank black sheets around calibration hole were removed
four 20-inch PMTs are moved to open tank
wire hanging frame was assembled around calibration hole

6. Install grid PMTs

7. Install cosmic-ray pipe
after pure water were filled again into tank, four pipes (1m long each) were inserted into calibration hole.
muon events are triggered by coincidence of two scintillation counters at the both ends of pipes

8. PMT trouble
we had a trouble that signals from some PMTs cannot be seen after installation into water
color of photo cathode plane had been changed

9. Cracks in PMT
According to the investigation by Hamamatsu company, some cracks were found between metal frame and window glass
we couldn’t understand the cause of the crack yet. possible causes are:
PMT supporting was too tight?
shrinkage of adhesion bond was too strong?
we asked to produce additional five PMTs with softer adhesion bond
we took data with incomplete PMT setup

10. PMT grid configuration
data were taken in these three configurations :
shifted vertically (dz=30~70cm in 5cm intervals)
shifted horizontally (dx=0,20,32cm)
inclined (q=30,45 degrees)

11. Run summary data were taken for 19days (Jul-22 to Aug-9)
vertical
Run# Z(cm) configure Start time Runtime N
horizontal Jul 22, 12: h07m
horizontal Jul 23, 13: h03m
horizontal Jul 24, 08: h30m
horizontal Jul 24, 13: h35m
horizontal Jul 25, 13: h39m
horizontal Jul 26, 13: h39m
horizontal Jul 27, 13: h41m
horizontal Jul 28, 13: h09m
horizontal Jul 29, 13: h26m
horizontal Jul 30, 13: h43m
horizontal(20) Jul 31, 14: h43m
horizontal(32) Aug 01, 14: h41m
horizontal(60) Aug 02, 14: h40m
inclined(30deg) Aug 03, 15: h26m
inclined(45deg) Aug 04, 15: h26m
inclined(45deg) Aug 04, 19: h31m
inclined(45deg) Aug 05, 11: h42m
horizontal Aug 05, 17: h35m
horizontal Aug 06, 23: h41m
inclined(30deg) Aug 07, 13: h59m
inclined(45deg) Aug 08, 01: h30m
inclined(45deg) Aug 08, 22: h08m
horizontal(20) Aug 09, 09: h32m
horizontal
inclined
4 PMTs
8 PMTs
data were taken for 19days (Jul-22 to Aug-9)
399 hour and events in total
data were taken with 4 PMTs and 8 PMTs

12. CRP muon events CRP muon rate ~ 0.01Hz (~1000 events per one day)
reject
reject
CRP muon rate ~ 0.01Hz (~1000 events per one day)
Events selection is applied by total charge so far
still need further backgrounds rejection

13. Charge distribution Preliminary 1 3 1 2 3 4 2 4
more Cherenkov photons were observed for centered PMT

14. Nhit distribution Preliminary
dz=30cm
dz=55cm
dz=35cm
dz=60cm
dz=40cm
dz=65cm
dz=45cm
dz=70cm
dz=50cm
Nhit distributions are compared for data of different vertical positions
increase of Nhit value can be seen as dz increases

15. Nhit distribution (cont.)
Preliminary

16. Summary and To do Summary To do
fiducial test was carried out at 1kton tank
we had some trouble in grid PMT
difference of Nhit distributions due to vertex positions are confirmed by data
To do
more detailed analysis (reduction, reconstruction, shadow effect, etc.)
calibration of grid PMT and electronics
comparison with Monte Carlo
simulation study with 2km detector and nm beam flux