1. LHCb Velo: commissioning, performance and High flux tests.
K. Akiba
On behalf of the Velo group

2. LHCb VErtex LOcator Muon HCAL ECAL RICH2 Tracker Magnet TT RICH1 VELO
Outer/Inner Tracker
Silicon sensors
BEAM
BEAM
Kazu Akiba
RD09 Firenze 2

3. Velo – A Closer Look Cooling manifold 21 +2 modules
2 retractable detector halves:
21 stations per half with an R and Ф sensor
Bi-phase CO2 cooling system
Injection
6 cm x y
Cooling manifold
Stable beams
21 +2 modules
Kazu Akiba
RD09 Firenze

4. Even Closer Electronics Cooling:
Thermal highway to remove 18W (ΔT=20C)
CO2 evaporator
Mechanical Support
-sensor
R-side circuit
-side circuit
R-sensor
Thermal
Pyrolythic Graphite
Kazu Akiba
RD09 Firenze

5. after 3-4 years [~8 fb-1]: Replacement under construction
Sensors
300 μm n-in-n strip sensors (Micron Semiconductor)
Double metal layer for signal routing
R measuring sensors:
Pitch=40-102μm
Non uniform type inversion (2fb-1)
512
strips
Radius (cm)
512
strips
1385 outer
strips
683 inner
strips
Depletion Voltage
512
strips
512
strips
Radius (cm)
Ф measuring sensors:
Pitch=36-97μm
VELO closest detector to LHC!
expected radiation dose:
1.3 · 1014neq/cm2/year at r = 0.8 cm
5 · 1012neq/cm2/year at r = 4.2 cm
after 3-4 years [~8 fb-1]: Replacement under construction
Kazu Akiba
RD09 Firenze

6. Can we make it work?
Yes! – Detector in its very final commissioning stage.
Short description of the Controls and DAQ system
Some calibration plots.
Results from LHC injection tests.
Kazu Akiba
RD09 Firenze

7. Service electronics (84) Temperature monitoring Board (6)
DAQ/ECS
Shielding wall
VELO Half (x2)
LV CAEN
HV ISEG
Throughput Rate: 1 MHz
lOlOl
ADC
TELL (84)
ADC
ADC
ADC
Service electronics (84) LV
delays
Timing & trigger system
60m
analogue
cables
GBE
FPGAs
ECS
25m
Control Board (14)
ECS
Temperature monitoring Board (6)
delays
Optical receiver
Kazu Akiba
RD09 Firenze

8. Working State Test Pulse Noise Measuered with Noise:
Noise = offset + slope* Capacitance.
Test Pulse
Noise
Kazu Akiba
RD09 Firenze

9. LHC shots on TED No Cosmics for the Velo Results from last run:mm
No Cosmics for the Velo
Results from last run:
6-7th of June.
Main objectives:
Timing
Online monitoring
Tracking
Alignment
Determination of the detector position
TI8
LHC mm
Transfer line External beam Dump.
340m before LHCb, along beam 2
Aquired around 10k Tracks.
Kazu Akiba
RD09 Firenze

10. Time Shape Fit
Timing
Event by event pulse shape fit (25 ns spaced steps)
The procedure to tune the timing was tested with data acquired on the TED.
Can set the time with precision better than 2 ns with ~100 cluster/sensor/step
Time (ns)
Clusters
ADC Counts
Average fit, with fine steps (6.5 ns)
Time (ns)
Can set the time with precision better than 2 ns with ~100 cluster/sensor/step
Kazu Akiba
RD09 Firenze

11. Pulse Shape Time after peak (ns) Pre-spill % Spillover S/N loss 2.0
2.0
24.5 1
4.0
21.8
1.6 2
6.2
19.2
1.5 3
9.2
16.8
2.2 4
13.0
14.6
4.4 5
17.5
12.5
6.4 6
22.9
10.5
8.7
Amplitude
Peak (ns)
Constant
(offset)
Spillover = Peak +25ns /
Pre-spill = Peak - 25ns /
4 ns
+4 ns
Fractional charge
Kazu Akiba
RD09 Firenze
Fraction of the charge
Strip Length (mm)

12. TED’s Signal Use clusters on tracks and corrected for path-lengths
Phi: 34.4
R: 32.8
Signal to Noise:
Phi: 20
R: 18
ADC counts
ADC counts
Kazu Akiba
RD09 Firenze

13. Resolution Expected resolution vs track angle LHCb tracks TED tracks
Preliminary
TED tracks
Expected resolution
vs track angle
LHCb tracks
Kazu Akiba
RD09 Firenze

14. Pseudoefficiency by interpolation
Exp.
Rec.
Very
Preliminary
R sensors 97.2 %
 sensors 97.5 %
Limited search window:
5 of resolution + Tolerance of 100 m (5 mrad)
Mult. Scatter.
Higher Efficiency expected for
Collision data.
Kazu Akiba
RD09 Firenze 14

15. First evaluation of 2 halves distance
Preliminary
Resolver x distance 2 mm
Distance measured with 255 tracks:
2.163 mm ±0.08
The halves were moved by 450 m.
Distance measured with 852 tracks:
2.611 ± 0.09
Preliminary
Relative distance between the halves measured: 445
Kazu Akiba
RD09 Firenze

16. Some Tracks
Kazu Akiba
RD09 Firenze

17. Should we be afraid of LHC?
The Velo sits very close to the beam
Beam incidents are not to be excluded:
incomplete or unsynchronized kicker fire
wrong magnet settings in transfer line LHCb
wrong magnet settings in the LHC
Take a Velo Module to a quasi LHC incident scenario:
Velo High Particle Rate Test A.K.A. Zap Test.
Kazu Akiba
RD09 Firenze

18. PS Booster Proton beam with 1.4 GeV energy Intensity: 2x109 – 9x1012 p
Beam spot: a few mm
Bunch length: ~200 ns
Resto 2
Main
bldg
Compare with LHC
Pilot injection:
2x109 protons (450 GeV)
300 µm beam spot
0.4 ns bunch length
Full luminosity L=1034
4x1013 protons/cm2/bunch
288 bunches
Kazu Akiba
RD09 Firenze

19. The victim Mounted in the beam line LHCb/Velo spare from production
Cooled to +1 ˚C (LV on)
Florescent screen to view the beam
Insert/retract from beam line
Remote control and read-out
LHCb/Velo spare from production
Kazu Akiba
RD09 Firenze

20. Beam images Combined R-Φ sensor Beam line camera on front-end data
scintillating screen
Kazu Akiba
RD09 Firenze

21. Measurements No measurable damage up to
Intensity steps: 2x109, 2x1010, 2x1011, 2x1012 , 9x1012
Each step: LV/HV off, LV on/HV off, LV on/HV 150 V , LV on/HV 300V
Each beam ‘shot’ follows the same pattern
A set of standard measurements
I/V of both sensors
Noise & pedestal data
Test pulse data.
Insert the module, acquire during the shot
14 consecutive triggers of front-end data: 350 ns.
Repeat the same set of measurements
Shots on two sensor positions
Shots on five front-end chips (only LV on/off matters)
No measurable damage up to
300V bias on the sensor
2x1011 (LV on) on the FE chips
Kazu Akiba
RD09 Firenze

22. Survival Proofs Test pulse response
@ ‘booster’: in-situ after a few shots at 2x109
‘lab’: lab measurement after the full program
Gain difference due to different analogue drivers/receivers
Bad channels identical to production QA
Kazu Akiba
RD09 Firenze

23. Thermal image: No hot-spots
Kazu Akiba
RD09 Firenze

24. Summary The Velo detector is ready for data taking with the LHC.
At least one module tested against (and survived) a “beam like incident” particle rates.
Kazu Akiba
RD09 Firenze