1. Integration of the e+ elements
General discussion
Integration of the e+ elements
Laszlo Liszkay
Positron line
Buffer gas trap (BGT)
Multi-ring trap (MRT)
Reaction chamber
BGT
Buncher
Field exit
Lenses
Target
BGT1
BGT2
BGT3
MRT1
MRT2

4. Present status of the different parts
BGT: being tested
MRT: magnet awaiting commissioning, electrodes to be installed
Buncher/lenses assembled, to be tested
Target: under construction

5. Differences between the Saclay and CERN installation
No MRT in Saclay
Buncher directly after BGT
Higher frequency (1 Hz?)
Different pulse energy/intensity at buncher
Different magnetic field at magnetic field exit
At CERN, no access to the beam during operation
All beam diagnostics with remote control
Can we use the MRT trap at first in a shoot-through configuration, without trapping, in the first measurements? (in order to perform measurements before the trap works) Or just in a simplified configuration (rectangular potential well, switches)?

6. Can we use the MRT trap at first in a flat-field configuration, without trapping, in the first measurements? (in order to perform measurements before the trap works)
Or just in a simplified configuration (rectangular potential well, switches)?

7. DN100 straight tube + solenoid
Diagnostics cross
DN100 bellows + coils
DN100 straight tube + solenoid
Do we need a pump here?

8. Integration of the positron source and the buffer gas trap
Beamline: to be completed
bellows + coils
tube with solenoid
cross + pump if needed (decision?)
Other interactions:
Information from linac (frequency, trigger, on/off)
Pressure values & position of the gate valve
Who?
Purchase/manufacture vacuum parts (DN100CF tube, bellows) - length depends on other choices
Wind coils
Prepare support (NORCAN or similar)
When?
Before the installation of the buffer gas trap

9. Do we need one more pump here?
Missing: DN100 bellows
DN100CF valve

10. Integration of the buffer gas trap with MRT
Connection with bellows (available) if no extra pump is needed (decision)
DN100CF gate valve (check if available)
Trigger: ejection from BGT
Other information exchange: pressure, position of the valve
To do: calculate magnetic field (put together existing models)
Who?
Has to be done together with the assembly/testing of MRT
When?
Parts can be found:ordered immediately
Possibility: new chamber to replace the old RIKEN one
With better magnetic properties if possible
With large enough tube for pumping

11. DN100 cross for pumping
(which pump?)
+ buncher
cross (available or – better - new DN160) + coils (available) + power supply (use reserve + buy new)
Or totally new chamber/cross (time + manpower)

12. Integration of the MRT trap with the target chamber
Cross + coils (exist in DN100CF)
Pump: which type?
Cryo: best but very expensive (>20k€)
Ion getter: distortion of the magnetic field
Turbomolecular: pressure limit too low(?)
Trigger:
Injection trigger from BGT
Ejection trigger from ELENA (+ delay+gate/veto)
Other information: vacuum pressure, valve position

13. Diagnostics NaI/CsI CsI (~4 targets) MCP MCP + scint. MCP CsI/NaI
Faraday cup (e+)
PbWO
MCP (atoms)
MCP (ions)
Tracker (anti~)
Faraday cup (p)

14. Beam diagnostics
Detection of the annihilation radiation
CsI+diode: at the moment, problems with direct 511 keV calibration (noise); no time information
NaI + PM: more robust signal but sensitive to magn. field; no time information
Plastic + PM: difficult to calibrate, sensitive to magn. field; good time information
PbWO: difficult to calibrate, sensitive to magn. field, good time information; works well with high intensity
Beam shape detection
MCP (double) + phosphor screen + camera time information is possible
Faraday cup for direct charge detection
Must capture secondary electrons
Only at higher pulse intensity (?>1M e+?)
Can be used to verify calibration of scintillation detectors

15. Calibration of the detectors
Calibrate one or two NaI (or perhaps CsI) detectors by
Measurement of the 511 keV gamma line
Determination of the mean signal amplitude per positron (G4 simulation, verified by measurement)
Calibrate the other detector with the help of the calibrated ones

16. Data acquisition:
At the moment, we have only destructive beam diagnostics devices
Only one can be used at a time, so several detector can use the same data acquisition device if needed (by using a signal switch)
The only continuously operating data sources of the positron line will be the gamma detectors in the reaction chamber
We should check if a non-destructive diagnostics device (toroidal current monitor?) is possible when the MRT trap works

17. Different parts
Beam diagnostics at the beam exit from the bunker: oscilloscope at the moment, can be switched to PXI card+amplifier if we have enough money
BGT – PXI card, working (archiving to EPICS?)
BGT – MCP + camera, working (manual, manual archiving)
Reaction chamber: oscilloscope (scintillator detectors + MCP signal)
Reaction chamber: MCP+camera (to be ordered, same as MRT)

18. Timing signals:
BGT works with internal timing + gives trigger signal to MRT
MRT ejection is triggered by ELENA (ns jitter)
Laser triggered by ELENA (+ pre-trigger)
Atom/ion detection is triggered by ELENA (10ns jitter is OK)