1. Prototype Vertex Detector
NA61/SHINE Collaboration Meeting, Belgrade, May 2013

2. Outline 1. VD dimensions 2. Prototype acceptance optimization (M-26)
VTPC2
1. VD dimensions
2. Prototype acceptance optimization (M-26)
3. Simulations with prototype VD geometry
4. Project plan

3. NA61/SHINE detector – top view
VTPC2
Vertex Detector (VD)

4. VD in geant4 VDS1 : 5 cm VDS2: 10 cm VDS3: 15 cm VDS4: 20 cm VTPC2

5. VD in geant4 MIMOSA-26 sensors Carbon fiber support
VTPC2
MIMOSA-26 sensors
Carbon fiber support
Water cooling tubes
Vessel:
Rectangular top/bottom plates
Trapezoidal left/right plates
→ same length of carbon leader
→ similar distance between top/bottom plates and VDS1-VDS4
→ flat micro cables variation in length +/- 2cm
VTPC1

6. Signal track distribution at 158 AGeV in VDS1
VTPC2
2x4 cm2
VTPC1
The figure shows hits (x,y) distribution generated by signal tracks is Vds1. The dashed boxes represent the cuts. We found that ~99.5% of signal tracks is localized within the box 2x4cm2.
As you can see, to cover the remaining 0.5% we would need to extend the cut in the x direction for almost factor of 2.

7. Signal track distribution at 158 AGeV in VDS2
VTPC2
4x8 cm2
VTPC1
For stations Vds2-Vds4 we just extend size of the boxes in proportion to their distance from the target. So we got dimensions: 4x8 cm2, 6x12 cm2 and 8x16 cm2 for Vds2, Vds3 and Vds4, respectively. The signal lost is kept below 1 % for each station.
For Pb+Pb at 40 AGeV the signal lost is on the level of 4% for the same cuts.

8. Signal track distribution at 158 AGeV in VDS3 and VDS4
VTPC2
6x12 cm2
VTPC1
8x16 cm2

9. VDS4 prototype optimization
VTPC2
VTPC1
Requiring that kaon or pion from D0 decay hit area covered by M-26 sensor
Looking for kaon/pion location from the same D0 decay

10. VDS4 prototype optimization
VTPC2
VTPC1
Optimal location of the second sensor:
1. covers area with high correlated yield → maximize D0 acceptance
2. leads to up-down symmetry

11. VDS4 prototype 4 sensor layout
VTPC2
VTPC1

12. Layout of prototype vertex detector, setup1
VTPC2
Vds4 (20cm)
Vds3 (15cm)
VTPC1
Vds2 (10cm)
Vds1 (5cm)
Full layout:
12 M-26 sensors
8 leaders (1.5x22 cm2) fixed on both sides to aluminum walls
Carbon fiber leader

13. Simulation results: prototype setup1 geometry
VTPC2
500k 0-10% central Ar+Ar at 158 AGeV
Background suppression cuts optimized to central Pb+Pb at 158 AGeV
(cuts may be relaxed for Ar+Ar/Ca)
~ 10 D0 + D0bar
For “no Pid” analysis signal significance might be too low.
For 500k central events SNR~2.5
VTPC1

14. Alternative geometry, setup2
Marek and Michael have criticized setup1 geometry claiming, that sensors location overlap with region of low acceptance
(|y|>0 x=0). They suggested to go to y=0 and |x|>0
VTPC2
VDS4
VDS3
VTPC1
VDS2
VDS1
Acceptance is defined by VDS4

15. Simulation results: prototype setup2 geometry
VTPC2
500k 0-10% central Ar+Ar at 158 GeV
Again cuts are optimized to central Pb+Pb at 158 AGeV
(cuts may be relaxed for Ar+Ar/Ca)
~ 20 D0 + D0bar
For “no Pid” analysis S/B=11
and SNR= 4.6
Measurement with the setup2 geometry seems to be feasible if we collect ~500k central events
(and if HSD yields are not significantly over-predicted)
VTPC1

16. Read-out connections scheme
outside helium vessel
Inside helium vessel
VTPC2
VTPC1
Aluminum frame
TRBv3
Standard cables/connectors

17. Read-out connections scheme
VTPC2
outside helium vessel
Inside helium vessel
VTPC1
Aluminum frame
TRBv3
Voltage
supply
Standard cables/connectors

18. Work Plan Nowa Electronika: M. Kajetanowich
+ Oscar, P. Korcyl (software)
T. Barczyk
Grigory Feofilov
???
People from task 1
+ Andras, Zoltan
P. Staszel, Y. Ali …..
Whoever wants to contribute,
Zoltan, PS, R.Planeta,
J. Brzychczk

19. Time plan 1. Proposal submission by June the 17-th (2 years)
2. Founds available late 2013
3. Purchases (M26, LV, Water Cooling Plant, TRB) late 2013 – beginning of 2014
4. Work in parallel on read-out, cooling system, carbon support mid 2014, sensors quality checks and integration on support
5. Integration of the system and tests on cosmics with DC (in Krakow) → will allow for synchronization test
6. Preparation for test at CERN: late 2014, beginning 2015.
7. Integrated test for Ar+Ca: Feb. 2015
– test data analysis, reco. software development

20. Backup Slides

21. D0→ K+ π- , 200k 0-10% cent. Pb+Pb at 158 AGeV
VTPC2
S/B=13
For 50M events:
SNR = 193
40k D0+D0bar
S/B=15
For 50M events:
SNR = 178
34k D0+D0bar
VTPC1
S/B=6.6
For 50M events:
SNR = 163
31k D0+D0bar
S/B=9.6
For 50M events:
SNR = 155
26k D0+D0bar