WG4 summary
•
•
•
•
•
Film Storage and book-keeping
Scanning Quality Control
Cosmic Ray Density
Vertex Confirmation
Vertex Location
WG4 summary
• Film Storage and book-keeping
– First version ‘Brick Tracer’ ready to use ( C. Bozza )
• Scanning Quality Control
– SUTS ( K. Morishima )
– ESS ( C. Bozza )
Brick tracer
http://operaweb.web.cern.ch/operaweb/internal/index.shtml
Cristiano Bozza – European Emulsion Scanning Group – Nagoya Jan 2008
3
WG4 summary
• Cosmic Ray Density
– Aim of cosmic ray exposure is to provide alignment for
momentum measurement and decay search.
– Data shows we can go down to ~1/5 while keeping alignment
accuracy. ( A. Ariga )
– Brick deformation can be corrected using Cosmic Rays during
transportation ( S. Takahashi )
• now ~6micron rms whole OPERA film WITHOUT cosmic rays
• Further improvement is being studied.
• One can apply this method for Bricks with black CS to have have
NO cosmic ray exposure.
• For normal bricks we can use cosmic rays in larger area for
alignment.
This method requires a brick should be made of emulsion sheets
in a single pack.
1.4cm x 1.4cm x 11plates
dx
369 tracks in scanning area
(dx) = sqrt(3/2)*(x)

From the point of alignment.
 Higher cosmic density doesn't give higher resolution.
 1/3~1/5 of current exposure is enough to get same
alignment accuracy(1micron).
WG4 summary
• Cosmic Ray Density
– Aim of cosmic ray exposure is to provide alignment for
momentum measurement and decay search.
– Data shows we can go down to ~1/5 while keeping alignment
accuracy. ( A. Ariga )
– Brick deformation can be corrected using Cosmic Rays during
transportation ( S. Takahashi )
• now ~6micron rms whole OPERA film WITHOUT cosmic rays
• Further improvement is being studied.
• One can apply this method for Bricks with black CS to have have
NO cosmic ray exposure.
• For normal bricks we can use cosmic rays in larger area for
alignment.
This method requires a brick should be made of emulsion sheets
in a single pack.
Deformation map
between film 1 - 2 @transportation
50micron
Deformation map
between film 1 – 2 @brick
50micron
difference (transportation - brick)
(film 1 – 2)
RMSx=2.4micron
RMSy=1.4micron
10micron
Deformation seems conserving between transportation and brick.
Virtual alignment
1cm
X-ray mark
･Used several films of brick:36565
exposed CR
･Scanned full area
･Important to read X-ray mark accurately
for accurate alignment
y
– Trying now
･Instead of X-ray mark,
used tracks at area near the X-ray mark
film
Lead
x
d
･Global correction is used tracks at area
near the X-ray mark.
･Local correction is used tracks
at transportation
film
･After virtual alignment,
I check position difference using brick track
Position difference
plate 25 - 26
dx
dy
[micron]
offset[micron] = ( -13.2, 2.2 )
RMS[micron] = ( 5.8, 5.8 )
Position difference have offset.
[micron]
Prospect for offset
If films curl at transportation
offset appear.
transportation
CR
after scanning
If curl effect contribute
offset should be had same value.
Offset for several
combinations
film1 – film2
offset
dx[micron]
offset
dy[micron]
25 – 26
-13.2
2.2
26 – 27
-17.2
-2.4
27 ｰ 28
-9.7
1.4
Offset is same within several micron.
WG4 summary
• Worries about “reducing cosmic ray density” exists … but
– Some scan back using X-ray marks were tried also in Europe side.
Lyon ( L. Arrabito )
– Cross check can be done soon using brick data taken so far.
WG4 summary
• Vertex Confirmation
– Volume scan procedure using SUTS ( T. Fukuda )
– Summary of events
Nagoya ( U. Kose, N. Kitagawa )
Bern ( C. Pistillo )
Lyon ( L. Arrabito )
• Vertex Location
– NO cosmics for bricks with Black CS
Presentations in A. Ariga and S. Takahashi -> Alignment w/o cosmics
– Bern NC event ( I. Kreslo )
One vertex related to cosmic rays
One vertex outside a brick
No CSD tracks
TT match
No Veto tracks
• Shift management and human organization
– Homework for each lab
ECC with black CS
(current Nagoya strategy.)
1.General scan the downstream
plates(3~5).
2.search vertex candidates.
3.Scanback or Direct vertexing.
• Strong worry about the 2nd, 3rd,
vertex by cosmic ray.
• --> no cosmic on the ECC with
ECC
black CS.
downstream
• Next talker, Takahashi.
NC event 179312944
Volume scan around vertex
577
748
2938
1211
450
Tracks are
visible in veto
=> This is NOT
a neutrino
event, but HE
cosmics
reaction
After scanback of ~1300 tracks two interesting vertices found
After scanback of ~1300 tracks two interesting vertices found