MuCool / Linac Diagnostic Beamline and MTA facility:

1. MuCool / Linac Diagnostic Beamline and MTA facility: External Beams Dept. C. Johnstone, + others Review Nov. 30, 2005

2. Purpose: • test the basic techniques and components proposed for muon ionization cooling and • provide accurate measurements of linac beam properties – important for future, stable high-intensity running of the downstream accelerators.

3. Description: • The new beamline and facility consists of • 15 Hz pulsed-magnetic extraction system which diverts an entire Linac macropulse into the new beamline • An ~50 m long beamline which feeds and ends in experiments housed in a 20’ x 40’ hall; the Mucool Test Area (MTA) • Using civil construction and resources that remain from the 400-MeV Linac Upgrade; this project is considerably economical. • The experimental hall is shielded and separated from the Linac by 12’ of concrete blocks— the beamline penetrates through these shield blocks to the hall • The new facility is capable of: • Accepting full Linac beam intensity (1.6 x 1013 protons @ 15 Hz) to within the radiological limits imposed by the current state of shielding and radiological controls

4. MTA facility: Plan View

5. Low-loss Beam Extraction from Linac • Extraction to MTA • Begins upstream and continues downstream of 400-MeV chopper to contain H- magnetic stripping losses to 10-4 level. • Requires 10” movement of Q74 upstream* • The entire Linac macropulse is extracted (the length of the macropulse may be varied from 2-50 by the 750-keV chopper. • Pulsed extraction magnets: • Pulsed extraction magnets: two “C” magnets • One 3 magnet upstream and one 7.5 magnet downstream; single power supply for both • >1” of clearance/no conflicts with 400-MeV line • No 400-MeV vacuum interruption for installation/removal • Design is complete; bids are in; awaiting final division budgets *kicking beam through Q74 causes a large displacement in the 2” Linac beampipe with accompanying high losses.

6. 400 MeV Linac Enclosure Ramp enclosure wall Ramp trajectories ~2m Extraction Drifts

7. H- Extraction Requirements • Beam entering ramp requires ~30 of bend relative to Linac • Dipole field strengths • 7kG to avoid stripping H-, • upstream of chopper, ~6kG (Chopper is highly sensitive to electrons and sparking) • First component to clear is Q2 • Controls beam separation to Booster/diagnostic line • Cannot be moved; tricky to align • Requires 11” to clear manifolding, 13-15” beam center to center relative to transfer line • Next element to clear is lambertson • Dipole (CR) conveniently fits next to transfer line between Q2 and lambertson • If CR dipoles are used (10 max) another one is required to avoid enclosure corner, 45 total is required for ramp curvature and align beam parallel with the experimental hall enclosure.

8. Linac modifications: Q74 moves ~10’ upstream BLD – will be removed to make space for quad Quad to be moved

9. Pulsed Extraction System: Two C Magnets Two C magnet: 10”, 25” long, 6.2 kG, 3, 7.5 bends Chopper

10. Extracted Beam trajectories

11. Critical Path: C magnets Beam tubes in longer magnet ~1/16” spacing between beam tubes @entrance to magnet 4.869” (0.1126 m) X See example coil and lamination details in text + tables R1.625” (0.04128 ) Gap: 2.000” 2.125” min (0.0540 m) 1.949’ (0.0495 m) 4.618” (0.1173 m) Example coil (0.4096” Cu): 1.850” (0.0470 m) sssssssssssssssssssssss 10” 0.254 m IRON z Tube  2”  0.0625” WALL 304 SS  1.5” Beam Tube  25.866” (0.6570 m) IRON z z 2” schedule to pipe 3.005 QUADRUPOLE 16.75” slot (0.4254 m) (17.8” total flange to quad steel) Z TUBE 304 SS  3.25” 0.0625” WALL 76.281” (1.9375 m) 4.563” (0.1159 m)

12. Diagnostic Line Design - • New design incorporates • 10 m straight for transverse emittance measurements of linac beam • 50 cm low beta waist at center of straight • Order of magnitude change in beam size • Access to low beta focus point • Dispersion suppression • Inexpensive straight bore through shield blocks • Simple, stable match to linac based on linac FODO cells (~90) • High (~7m) dispersion point for momentum-spread measurement

13. Optical functions

14. Half-width beam size: Experimental Hall Shield blocks MW1 MW2 MW3

15. Layout, plan view Shield blocks

16. Transverse emittance measurement

17. Emittance error analysis: • Resolution of profile measurements: • A conservative estimate of the systematic error, R1, in measuring the width of a wide beam (in our case, ~50 mm full width) using 1 mm wire profile monitors would one wire for determination of the 95% width above background. In this case the 1 mm wire spacing dominates the measurement uncertainty for an arbitrary beam profile. (Linac beam is not Gaussian.) Since these are half-widths, R1 0.5 mm. • As the width decreases, determination of the profile shape may dominate the systematic error and the absolute (but not relative) resolution error decreases. (It is important to increase the resolution of the profile monitor itself, to 0.5 mm spacing, for example, at the waist). A 10% measurement of the profile width applying fitting techniques gives a 0.5 mm error for a ~5 mm beam full width, or Rw ~0.25 mm

18. Emittance measurement error:

19. Changing the systematic error

20. Operational details of Diagnostic Tune • Minimum beam stay clear – • 0.3” (8mm) in upstream 2” chopper mating flange and triplet quadrupoles based on 10  mm-mr linac emitance. • Dispersion suppression can be checked and tuned by : • varying linac output energy and varying last CR dipole strength • Beam will be “steered” into hall using trims after the diagnostic straight • Low-beta waist can be adjusted and focused onto the second multiwire (just downstream of shield blocks) • Using the quad low-beta triplet • Critical Devices: • Pulsed extraction magnets • Beam stop upstream and downstream of shield blocks • Occupancy and radiological controls • Beam stops provide unlimited occupancy in experimental hall • Postings, fencing, eberm module will allow us to run at ~1 Hz and full linac intensity • Pulsed power supply will be hard-wired to 1 Hz.

21. Low-loss beam tune for MTA running • Beamline can be re-tuned for MTA experiments to achieve the lowest-loss optics. One example is given below with momentum spread included. The peak beam envelope is reduced by 1 cm in the half width (2 cm full width). If a polarity flip of the quadrupole is allowed, even smaller beam envelopes can be achieved.

22. Component Inventory

23. Power supplies and power requirements

24. Resource Synopsis: M&S Beamline Components With the exception of the C magnet, all beamline components are available quadrupoles and dipoles trim magnets diagnostics beam stops instrumentation and controls such as an eberm system Power Supplies With the exception of the pulsed power supply, all major supplies and a number of smaller ones are available dipole supplies misc quad and trim supplies Vacuum ion pumps are available (30 liters/min) misc vacuum components Water 55Linac water is available Tevatron sled available

25. Resource requests: Summary PPD C magnet PPD Machine shop: magnet stand fabrication/modify existing stands spool pieces TD magnet inspection and testing small repairs (hoses) AD (SWF) C magnet power supply labor Installation: vacuum, safety, water, power supplies, beamline, controls Muon Funds C magnet power supply parts electricians cable tray and civil (6” bore through shield blocks)

26. C magnet specifications:

27. C magnet specificatons cont…

28. Shutdown Tasks • Quadrupole move • Installation of new chopper flanges and gate valve • Further installation can then proceed independent of linac and as time and resources permit

29. DONE

30. DONE

31. Modifications to Chopper and its downstream endE. Black

32. Chopper Modification Drawings

33. New Chopper Parts: detail

34. New Chopper Parts: continued

35. Status of MTA/Linac beamline - summary • Line design complete and components identified • Final layouts and full engineering in progress • C magnet bids are in, contract awaiting budget decision for divisions • Q74 move and chopper modifications/gate valve scheduled for ’06 shutdown; A0 CR dipoles pulled from Tevatron enclosure • Further installation can proceed without vacuum interruption/disruption to Linac or Booster • Installation complete in ’07 shutdown