1. Region I: stringing 1/3 done on 1st chamber!
Reg.1 stringing
May 25, 2011
Lead stringer hired; being trained at Jlab
Clean-room delivered; being set up
Readiness review in August

2. Region II: 2 built / 4 to go! Installing on the stringing fixture:
Feb. 2011
2nd crew hired: full 5-man crew!
2nd chamber strung; ready for testing

3. Region III – parts in procurement
Aluminum endplates; steel stiffeners
Carbon-fiber posts
Carbon-fiber / foam downstream shell
Our quality-control manager !

4. DC12 status – well underway
Drift Chamber Activity
% complete: 5/25/2011
Procure Wires, Pins, Feedthroughs
95%
Procure Endplates, Frames
83%
Build Boxes
17%
Outfit Cleanrooms
26%
Procure Circuit Boards
11%
String Chambers
5/27/11 Report
Wires are all in hand except for last 20% of Reg.3 guard wires; need to be stronger than Cu-Be because of higher tension; investigating 316SS
RFQ ready to go out for Reg.3 endplates, frames, posts, carbon shells
Build boxes as needed; build 3rd Reg.2 box and 2nd Reg.1 box in next 2 weeks
ISU cleanroom ordered; will be built in June, July 2011
Many details to be ironed out; orientation of connector, consistent labelling (HV & signal), single contract to clean, populate
Reg.2#2 stringing finished, Reg.1#1 guard wires done, ~ 400 field wires done

5. Physics Impact of (not having a)Vertex Detector
CLAS12 may begin operations with no forward vertex detector
what is the impact on physics?
Show impact on tracking resolution
Estimate impact of vertex cuts
Estimate impact of broadening of missing-mass distributions
small impact on non-strangeness physics
small impact on exclusive strangeness production
Need collaboration concurrence that these estimates are reasonable.

6. DC+FST – resolution for protons
(protons at  = 15°):
Compare
DC – alone vs.
DC + VTX
3-4 times better
8-10 times better
Much better vertex resolution with FST (and  resolution at high p)
Simulation & Reconstruction 10/30/ S.Procureur

7. DC+FST – resolution for electrons
(electrons at  = 15°, now from GEMC!):
20 times better
5 times better
FST largely improves the vertex resolution, ,  and p
Simulation & Reconstruction 10/30/ S.Procureur

8. Tracking Resolution with/w.o. vertex detector
Electron
(5 GeV/c, 15 deg.)
Proton
(2 GeV/c, 15 deg.)
Comments
with vtx
w/o vtx
dp/p
0.5 %
0.75 %
0.6 %
Modest changes to momentum and angular resolution;
 slight increase in running time to achieve same signal/noise in missing-mass dq
0.6 mrad
0.8 mrad
1.25 mrad df
2.3 mrad
4 mrad
3.5 mrad dz
1 mm
5 mm
2 mm
6.5 mm
Substantial changes to vertex resolution; impacts strangeness program, but small impact on exclusive production db
.15 mm
0.2 mm
1.8 mm

9. Physics Impact of (not having a)Vertex Detector
The vertex detector improves the pointing resolution of the CLAS12 tracking system at the target position substantially: from ~2mm to ~0.2mm in impact parameter resolution. For semi-inclusive identification of weakly-decaying strange particles, this can cut the non-strange background by a factor of 100 with a modest (~20%) loss of efficiency for the strange particle (e.g. a L baryon).
The vertex detector will not have a large impact on exclusive production of strangeness for those channels with a missing L because of the inherent narrowness of the L missing mass peak (mass just above threshold).
The vertex detector will afford a modest improvement in resolution for the momentum of charged tracks: ~30% improvement in dp/p for high-energy electrons, negligible improvement for lower-energy protons. Likewise, it will afford similar improvements in angular resolution for high-energy electrons and negligible improvement for protons. This will only marginally improve the ability of CLAS12 to identify particles by missing-mass techniques.
small impact on non-strangeness physics
small impact on exclusive strangeness production