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

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

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)?

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)?

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

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

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

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

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)

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

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)

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

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

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

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)

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)