1. LHC wire scanners status
BI/TB
05/03/2015
E. Piselli – B. Dehning – J. Emery
BE-BI-BL

2. Outline LHC wire scanners LS1 mechanical upgrades Electronics
Photomultiplier studies
New operational application

3. LHC wire scanners 8 linear wire scanners installed (4 spares) Beam 2
2 scintillators, filters and photomultipliers
Fast acquisition
Max speed: 1m/s
Wire size: 30μm
Aperture: 60mm
Beam 2
Beam 1

4. LS1 mechanical upgrades
Pre LS1 bellows had experienced few vacuum leaks and the maximum rating given by the manufacturer was scans.
During LS1 all bellows were exchanged but different stiffness and vacuum force of the new ones required new compensation springs.
The new bellows have been validated by calculation (P.Magagnin) and by functional observation with 1000 scans.

5. LHC BWS Firmware (board with 3 FPGA)
Electronics
LHC BWS Firmware (board with 3 FPGA)
Same running version in the PSB and PS since and in LHC since 2010.
Intensive use in CPS has shown its limitations.
Firmware release mandatory in order to: 1) Have a safe InitHW sequence (return from IN position) 2) Add extra safety necessary to avoid the ‘reset home problem’ 3) Mitigate about 1% of ‘lost Triggers ‘
4) Be able to move the scanner to the home position from any position

6. Electronics Where we are… Firmware Status: Next Steps:
Lost triggers
Firmware bug identified & fixed
New version tested in lab
Safe Init Hardware Sequence
Successfully tested in lab
Extra safety to avoid failure during Init Hardware
Inhibit relay to be switched ON if position difference too large
Next Steps:
Deploy new firmware on full CPS-type scanner test installation in 867
Two weeks of extensive testing with the new firmware for all identified failure scenarios
Deployment in LHC to be planned…

7. Photomultiplier studies
PHILIPS XP2243B
voltage divider
phototube

8. Photomultiplier studies
Signal OUT K A D1 D2 D3 D4 D5 D6
10KΩ 3R R R R
1.5R
470KΩ
680KΩ C1 C1 C1 C1 C1 C1 C1 C2 C2 C2 C3
R=220KΩ
C1=10nF
C2=112nF
C3=39nF
-HV

9. Photomultiplier studies
We have studied the response linearity of the photomultiplier...
Visible saturation from measurements...

10. Photomultiplier studies
Lab setup
Freq. generator
1Hz
Oscilloscope
Green led diode K A
Signal OUT
50Ω
-HV

11. Photomultiplier studies
We have performed different measurements:
@ 1800V and 2000V
@ different output current…1mA, 2mA and 5mA
@ different pulse width…500μs, 1ms, 2ms, 5ms, 10ms and 20ms (always 1Hz frequency)
2000V 1mA 500μs
2000V 3mA 2ms
2000V 5mA 5ms

12. Photomultiplier studies
Hamamatsu PMT specification in dynamic mode (ns scale):
To achieve 1% linearity Q*=100·Qsignal
Qsignal K A
We have added 3 decoupling capacitors (15μF each) in parallel to the 3 last ones in order to:
supply photomultiplier tube with an electric charge during the forming of the signal pulse
restrain the voltage drop between the last dynode and the anode

13. Photomultiplier studies
Signal OUT K A D1 D2 D3 D4 D5 D6
10KΩ 3R R R R
1.5R
470KΩ
680KΩ C1 C1 C1 C1 C1 C1 C1 C2 C2 C2 C3
R=220KΩ
C1=10nF
C2=112nF
C3=39nF
-HV 13

14. Photomultiplier studies
Signal OUT K A D1 D2 D3 D4 D5 D6
10KΩ 3R R R R
1.5R
470KΩ
680KΩ C1 C1 C1 C1 C1 C1 C1 C2 C2 C2 C3 C4 C4 C4
R=220KΩ
C1=10nF
C2=112nF
C3=39nF C4=15μF
-HV

15. Photomultiplier studies
2000V 1mA 500μs
2000V 3mA 2ms
2000V 5mA 5ms

16. Photomultiplier studies
B1 and B2 PM have been reinstalled in the machine…

17. Photomultiplier studies
We have few consequences after the modifications done to the system:
When HV is applied for the first time we have to wait about 30sec
HV will be left ON after each scan at least for 30’
Front end and application software needs to be modified
New studies will be performed using laser diode to verify linear response of PM output signal with light intensity
We are investigating on new PM

18. New operational application
Developed by M.Kuhn

19. New operational application
Can acquire data after a scan or get data from logging or measurement DB.
Emittance evolution through a fill (either bunch-by-bunch emittance or average emittance per scan depending on number of bunches).
Displays the bunch-by-bunch transverse profiles.
Displays bunch-by-bunch emittances per scan in a bar graph.
Developed by M.Kuhn and V.Kain 19

20. New operational application
User can scroll through bunch profiles and different scans.
All wire scanners in one application (scroll down).
Developed by M.Kuhn and V.Kain

21. New operational application
First fitting done in front end. Analyse button to fit the profiles with a five parameter Gauss. Common java package in all accelerators for fitting. Fit data will be send to logging database.
Developed by M.Kuhn and V.Kain

22. New operational application
User can choose between nominal beta function or measured beta function (stored in LSA) for emittance calculation.
Developed by M.Kuhn and V.Kain

23. New operational application
Number of bunches automatically chosen from sequencer. All circulating bunches are selected by default. Updated automatically. There is also a possibility to manually select or deselect bunches (in configure bunch selection).
Developed by M.Kuhn and V.Kain

24. New operational application
Particle type is always monitored via LSA. Application also works for ions now!
Developed by M.Kuhn and V.Kain

25. New operational application
In “configure scanners” voltage and filter of PMs can be set. Predefined settings can be uploaded. New gain scale: gain now in per mille!
In “configure acquisition” wire scanners can be enabled and disabled for a scan. Future possibility to launch multiple scans.
Scan button is pressed only once and all enabled scanners are fired one after the other.
Scanner status is always monitored. Photomultiplier saturation (colour coded) to be implemented after calibration.
Developed by M.Kuhn and V.Kain

26. Thanks for you attention…
Conclusion
All the wire scanners have been refurbished with new bellows and all the springs have been adapted differently for the horizontal and vertical axes
New firmware should avoid difficult situations observed in the past
PM have been modified for the saturation problems
Operational GUI is easier and complete
Commissioning and MD time have been requested
People involved:
P. Magagnin, R. Veness, A. Guerrero, M. Kuhn, L. Timeo
Thanks for you attention…