1. AEGIS positron transfer line
Daniel Krasnický
AEGIS meeting March 30, 2009
AEGIS e+ transfer line

2. Overview
We have used OPERA3D software from Vector Fields. For field calculations concerning only solenoids it uses Biot-Savart analytical solution for a given point.
The software has a built in particle trajectory calculation routine.
The trajectory calculation was done in a single particle regime.
In the first phase we tested the possibility to inject positrons into the 5T magnet from the center (between the 5T and 1T magnets).
Then we looked at the possibilities to inject from the AD side.
The transfer line is curretnly in relatively detailed stage of preparation, the limiting factor is the unknown positron accumulator and AEGIS/AD interface.
AEGIS e+ transfer line

3. The transfer line (TL) purpose
The purpose is to transport positrons from the positron accumulator (at max 0,2T) into the 5T magnet under these conditions:
e+ injection at max radius r = 2cm
after e+ cloud compression safe transport to 1T magnet
homogeneity of the main magnets needs to be preserved
In case of central injection – no rapid field change (B change max. 100Gauss/s)
In case of AD side injection – degrader & AD/AEGIS fail-safe vacuum separation
Minimum field during the transfer: 0,1T
Space for pumps, diagnostics, baking cables… etc.
AEGIS e+ transfer line

4. Central injection
The e+ central injection was a first choice, but after a couple of tests we abandoned it.
The guiding coil would have a field of the same order of magnitude as the local field → 1T and more → Superconducting
Injection and transport were not within the requirements
Central injection would also cause construction problems of the central cryostat section.
Positives: same AD-AEGIS connection as in ATHENA
AEGIS e+ transfer line

5. AD side injection
The injection from the AD side avoids most of the problems of the central injection
undisturbed 5T→1T transport
simpler central cryostat – easier acces for diagnostics
axially symmetric field in the central region
A problem with the vacuum separation arises
The experiments need to be disconnected from the AD vacuum (protection of AD in case of our catastrophic venting).
The vacuum separation foil has to be able to hold instant increase to atmospheric pressure and be as thin as possible (and from a material with a long radiation length).
Effect of this foil on the antiproton beam is under study by Andrea at Pavia.
A movable degrader in the cryogenic region has to be developed to allow for positron and other particles injection.
AEGIS e+ transfer line

6. AD side injection
A thin vacuum safe separation foil is used at the exit from the AD (30cm from the cryostat).
A movable degrader is located at the entrance to the catching trap.
Positrons are injected on axis by the use of warm coils.
AEGIS e+ transfer line

7. Transfer line, positron acc. & main coils
Side view: from left to right - The main AEGIS coils – the e+ transfer line – the positron accumulator
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8. Transfer line, positron acc. & main coils
Side view: from left to right - The main AEGIS coils – the e+ transfer line – the positron accumulator
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9. Transfer line, positron acc. & main coils
Side view: from left to right - The main AEGIS coils – the e+ transfer line – the positron accumulator
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10. Transfer line, positron acc. & main coils
Side view: from left to right - The main AEGIS coils – the e+ transfer line – the positron accumulator
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11. Transfer line, positron acc. & main coils
Side view: from left to right - The main AEGIS coils – the e+ transfer line – the positron accumulator
AEGIS e+ transfer line 11

12. Transfer line, positron acc. & main coils
Side view: from left to right - The main AEGIS coils – the e+ transfer line – the positron accumulator
AEGIS e+ transfer line 12

13. Transfer line with RT correction coils
Guiding coils are surrounded by correction coils (racetrack pairs) used for transverse path corrections
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14. The current TL design The positron TL uses two types of coils:
Main guiding coils – solenoids – create axial 0.1T field at all places of the TL.
Correction coils – racetrack, CP or solenoids – used for transverse particle path corrections.
The correction coils are in Helmholtz-like pair geometry
currents in the pair are oriented in the same direction
dipole field
particles bend in the direction of the correction coils field (not perpendicular - this is because of present strong axial field and the use of slow positrons)
The correction coils in the current design are needed only for one direction path correction – assuming no fringing field other than AEGIS 5T magnet.
Apart from the main guiding coils there are additional solenoids that help to overcome regions with lower than 0.1T field.
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15. The current TL design - versions
The transfer line is currently proposed in two versions
RT – correction coils are racetrack type coils
CP – correction coils are constant perimeter end coils (OPERA naming)
CP coils have these advantages:
are bent around the main guiding coils and thus require lower current densities compared to racetrack coils
Overall lower power requirement
The CP negatives are high construction cost
(estimate 7000 – CHF/coil)
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16. Transfer line with RT correction coils
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17. Transfer line with RT correction coils
RT version with fieldmap: Lower threshold 0.1T (blue), upper threshold 0.2T (red)
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18. Transfer line with RT correction coils
RT version with fieldmap – upper region: From right: PA, pumping section, UHV valve, 45°turn
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19. Transfer line with RT correction coils
RT version with fieldmap – turn region: Turn_Guide coil and FC_1&2 coils (to overcome diagnostics region)
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20. Transfer line with RT correction coils
RT version with fieldmap – middle region: 0.1T guiding solenoids and correction coils
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21. RT version with fieldmap – AEGIS-AD instrumentation region
Transfer line with RT correction coils
RT version with fieldmap – AEGIS-AD instrumentation region
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22. RT version with fieldmap – AEGIS-AD instrumentation region
Transfer line with RT correction coils
RT version with fieldmap – AEGIS-AD instrumentation region
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23. RT version with fieldmap – AEGIS-AD instrumentation region
Transfer line with RT correction coils
RT version with fieldmap – AEGIS-AD instrumentation region
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24. RT version with fieldmap – AEGIS-AD instrumentation region
Transfer line with RT correction coils
RT version with fieldmap – AEGIS-AD instrumentation region
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25. RT version with fieldmap – AEGIS-AD instrumentation region (close-up)
Transfer line with RT correction coils
RT version with fieldmap – AEGIS-AD instrumentation region (close-up)
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26. Transfer line with RT correction coils
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27. Transfer line with RT correction coils
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28. Transfer line with CP correction coils
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29. Transfer line with CP correction coils
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30. Transfer line with CP correction coils
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31. CP version with fieldmap – AEGIS-AD instrumentation region (close-up)
Transfer line with CP correction coils
CP version with fieldmap – AEGIS-AD instrumentation region (close-up)
AEGIS e+ transfer line 31

32. CP version with fieldmap – AEGIS-AD instrumentation region
Transfer line with CP correction coils
CP version with fieldmap – AEGIS-AD instrumentation region
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33. CP version with fieldmap – AEGIS-AD instrumentation region (close-up)
Transfer line with CP correction coils
CP version with fieldmap – AEGIS-AD instrumentation region (close-up)
AEGIS e+ transfer line 33

34. Transfer line with CP correction coils
AEGIS e+ transfer line 34

35. Transfer line with CP correction coils
AEGIS e+ transfer line 35

36. The current TL design TL uses warm coils & no water cooling
Coil plastic core/support of 5mm thickness
Coils warm up at max. 25°C in 100s
Total power is P = 6500W – 7000W (DC)
5T anticoil is at 60A/mm2 (current oriented same direction as 5T coils)
Initial conditions: 100eV positrons, +/-5mm from the PA axis
Positrons are injected into the 5T magnet at max 4mm from the axis
Effective path corrections are realized by correction coils
The transfer line is assumed to be turned on for approx s
No fast pulses needed
AEGIS e+ transfer line 36

37. The e+/- Transfer Line Transfer line can be used for:
e+ injection into AEGIS
electron injection into AEGIS
e+ ejection in transverse direction for other use
Transfer line cannot be used for:
heavy particles injection (p,Os, etc…)
cyclotron radius is too large thus they do not gyrate closely around the field line
For heavy particles injection a new channel is needed
the (only) probable space is in the AEGIS-AD instrumentation region
AEGIS e+ transfer line 37

38. The diagnostics
There are three areas for destructive faraday cup measurement
at PA pumping section
after the 45° turn
in the AEGIS-AD instrumentation region
Additional external annihilation detectors could be used
Magnetic field measurement in the zone will be done before the electron/positron runs.
By measuring the transverse field components, we can adjust the right current for the correction coils (or make additional correction coils).
AEGIS e+ transfer line 38

39. The vacuum The transfer line will be NEG coated
Space for bakeout cables (6-8mm) included
Space for two valves is included
VAT DN63 XHV all metal gate-valve: disconnecting AEGIS main cryogenic region from room temperature region.
Mini UHV DN40 VAT valve: disconnecting PA and the TL
Space for two DN100 pumps included
if larger neck needed (at PA) higher power in the P_G_1 coil needed as well
If we would be confident (& succesful) in the particle transport we can think of inserting gas flow restrictions into the TL pipe.
AEGIS e+ transfer line 39

40. The problems of the current design
No information about the pbar focusing and AD beam line
The current layout assumed DN63 pipes at the AD output and AEGIS input
Also if there are space restrictions due to AD beam line the geometry might change dramatically.
No information about the planned positron accumulator
The magnet used in the simulation was created by guess
especially dimensions and axial field are important
Dimensions of the AEGIS main vacuum chamber?
I assumed DN63 flange
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42.
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43. Thank you
Any (more) questions?

44. Magnetic flux Bmod along main AEGIS axis
Apendix
Magnetic flux Bmod along main AEGIS axis
(starting 1m from the centre between the main coils directed towards the 5T AEGIS-AD instrumentation region)
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45. Apendix Magnetic flux Bmod along slanted TL axis
(starting at AEGIS-AD instrumentation region ending at the 45° turn)
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46. (starting at the 45° TL turn, ending at PA)
Apendix
Magnetic flux Bmod in a +/-2cm band along the positron accumulator axis
(starting at the 45° TL turn, ending at PA)
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