1. P.-R. KettleMEG-Review July 20041 MEG Beam Line Studies  E5 Z-Branch Collaborative Effort !!! Effort !!!  E5 Z-Branch Collaborative Effort !!! Effort !!!

2. P.-R. KettleMEG-Review July 20042 Topics to be Addressed Overview Overview Current Component Status Current Component Status Beam spot size Beam spot size Summary / Conclusions Summary / Conclusions Beam Line Commissioning Schedule Beam Line Commissioning Schedule Overview Overview Current Component Status Current Component Status Beam spot size Beam spot size Summary / Conclusions Summary / Conclusions Beam Line Commissioning Schedule Beam Line Commissioning Schedule

3. P.-R. KettleMEG-Review July 20043 Beam Line Overview Beam Line Objectives Couple ‘Z’-Branch elements in shielding to the detector i.e. COBRACouple ‘Z’-Branch elements in shielding to the detector i.e. COBRA Stop maximum number of μ + in thinnest target with minimal background contaminationStop maximum number of μ + in thinnest target with minimal background contamination  No Iron allowed in vicinity COBRA → Solenoid coupling  28 MeV/c surface μ + beam with high transmission efficiency → Rate  Reject beam e + background e + /μ + ~ 10 →Wien Filter  Small beam spot size at target in COBRA → careful optics + collimator system + solenoid  Thin slanted target min. thickness for  → 37 mg/cm 2 CH 2 Tg at 22  + degrader system → 37 mg/cm 2 CH 2 Tg at 22  + degrader system Beam Line Objectives Couple ‘Z’-Branch elements in shielding to the detector i.e. COBRACouple ‘Z’-Branch elements in shielding to the detector i.e. COBRA Stop maximum number of μ + in thinnest target with minimal background contaminationStop maximum number of μ + in thinnest target with minimal background contamination  No Iron allowed in vicinity COBRA → Solenoid coupling  28 MeV/c surface μ + beam with high transmission efficiency → Rate  Reject beam e + background e + /μ + ~ 10 →Wien Filter  Small beam spot size at target in COBRA → careful optics + collimator system + solenoid  Thin slanted target min. thickness for  → 37 mg/cm 2 CH 2 Tg at 22  + degrader system → 37 mg/cm 2 CH 2 Tg at 22  + degrader system  E5 Area

4. P.-R. KettleMEG-Review July 20044 Beam Line Overview Contd.  Triplet I  Wien Filter E^B Separator  Triplet II  Triplet I  Wien Filter E^B Separator  Triplet II  Collimator system  Beam Transport Solenoid BTS  Degrader + Collimator system  Target system + He-Bag System  Collimator system  Beam Transport Solenoid BTS  Degrader + Collimator system  Target system + He-Bag System

5. P.-R. KettleMEG-Review July 20045 Recap Previous Main Results Triplet 2 1 Solenoid WIEN Filter Colli. Trip. µ+µ+µ+µ+ e+e+e+e+ e+e+e+e+ µ+µ+µ+µ+ Integrated Rate After Separator 4cm Tg.E @ 1800µA N µ ~9.4·10 7 µ + /s (1.7·10 8 µ+/s 6cm Tg.) N e /N µ > 9 N e ~ 8.7·10 8 e + /s Transmission Factors T Sep = (71±5)% T Colli = (90±5)% Integrated Rate After Separator 4cm Tg.E @ 1800µA N µ ~9.4·10 7 µ + /s (1.7·10 8 µ+/s 6cm Tg.) N e /N µ > 9 N e ~ 8.7·10 8 e + /s Transmission Factors T Sep = (71±5)% T Colli = (90±5)% Integrated Rate 4cm Tg.E @ 1800µA N µ ~1.3·10 8 µ + /s (2.3·10 8 µ+/s 6cm Tg.) Integrated Rate 4cm Tg.E @ 1800µA N µ ~1.3·10 8 µ + /s (2.3·10 8 µ+/s 6cm Tg.) “Z-Branch” P cent =(28.2±0.1)MeV/c ΔP/P =(7.9±0.6)% FWHM P Beam =(28.2±0.9)MeV/c Consistent with TURTLE & P-Slit settings/Calib. P-Spectra:  -Kinematic Edge (29.79 MeV/c) P-Spectra:  -Kinematic Edge (29.79 MeV/c) Theoretical func. P 3.5 folded with Gaussian ΔP/P + Const. Cloud µ + contribution

6. P.-R. KettleMEG-Review July 20046 Previous Main Results contd… Integrated Rate After PSC Solenoid !!! 4cm Tg.E @ 1800µA N µ ~6.1·10 7 µ + /s (1.1·10 8 µ+/s 6cm Tg.) Beam Spot: σ X ~ 5.3 mm σ Y ~ 6.5 mm Transmission Factor Solenoid T Sol = 71 % Integrated Rate After PSC Solenoid !!! 4cm Tg.E @ 1800µA N µ ~6.1·10 7 µ + /s (1.1·10 8 µ+/s 6cm Tg.) Beam Spot: σ X ~ 5.3 mm σ Y ~ 6.5 mm Transmission Factor Solenoid T Sol = 71 % With larger Bore i.e. BTS T>71% Integrated Rate 4cm Tg.E @ 1800µA N µ ~8.5·10 7 µ + /s (1.5·10 8 µ+/s 6cm Tg.) Integrated Rate 4cm Tg.E @ 1800µA N µ ~8.5·10 7 µ + /s (1.5·10 8 µ+/s 6cm Tg.) Triplet 2 1 Solenoid WIEN Filter Colli. Trip. µ+µ+µ+µ+ e+e+e+e+ e+e+e+e+ µ+µ+µ+µ+ µ/e Separation 11.8cm 7.2σ !!! µ/e Separation 11.8cm 7.2σ !!!

7. P.-R. KettleMEG-Review July 20047 Degrader & Stopping Distribution Measurements µ+µ+µ+µ+ CH 2 Tg e+e+e+e+ Foils CH 2 at focus Michel Range Curve using NaI: Measurement  Simulation Fix Degrader 600 µ GEANT say 580µ Nearly all Stopped in 400µ R ~ 870 µ CH 2 Degrader Target AIR Target Thickness vs. NaI Rate VAC Target Gives R Mean = 1150µ Equiv GEANT + TRIM 88% STOP in 400µ Tg !!! Solenoid Fix Degrader Var. Tg 88% stopped in 400µ CH 2 Tg.

8. P.-R. KettleMEG-Review July 20048 Component Status Beam Line Commissioning Started – Beam Line Commissioning Started –   E5 Zone totally refurbished, primary installation work – Completed  LHe + LN 2 Transfer Lines to zone – Design close to finished ready for ordering Triplet I Separator II Triplet II BTS-Solenoid New Old + New New New New Old + New New New Completed Completed PSCPSC PSC shown here

9. P.-R. KettleMEG-Review July 20049 Current Component Status – Triplet I Triplet I: FINISHEDTriplet I: FINISHED - Constructed from QSB Quadrupole magnets μE4 Triplet I: FINISHEDTriplet I: FINISHED - Constructed from QSB Quadrupole magnets μE4 Shutdown2004 Shutdown 2004 Until May Until May May 2004 Planned Insertion Shutdown → Delay due to LEMs Beam → Delay due to LEMs Beam planned 5th-6th May planned 5th-6th May → Delay Magnet Group → Delay Magnet Group due to LEMs Beam due to LEMs Beam Planned 19th May… Ready but !!! → Crane Problem → Crane Problem shielding cannot be removed shielding cannot be removed FINAL Insertion 2nd June May 2004 June 2004

10. P.-R. KettleMEG-Review July 200410 Current Component Status – Separators Old Separator II Old Separator II - previously used vertical separator - previously used vertical separator defective most of last Test Beam 2003 defective most of last Test Beam 2003 June 2004 Repaired with new power supply June 2004 Repaired with new power supply → to be used Commissioning Phase I, → to be used Commissioning Phase I, successfully conditioned to 195 KV successfully conditioned to 195 KV → ONLY available until August 2004 for MEG → ONLY available until August 2004 for MEG New Vertical Separator New Vertical Separator approved for MEG approved for MEG Originally So-called copy of LEMs separator Originally So-called copy of LEMs separator modified design underway & HV-parts ordered modified design underway & HV-parts ordered or delivered or delivered V max 200 KV V max 200 KV D plates 18 cm D plates 18 cm L eff 70 cm L eff 70 cm  Expected End 2004 !!!  Expected End 2004 !!! Old Separator II Old Separator II - previously used vertical separator - previously used vertical separator defective most of last Test Beam 2003 defective most of last Test Beam 2003 June 2004 Repaired with new power supply June 2004 Repaired with new power supply → to be used Commissioning Phase I, → to be used Commissioning Phase I, successfully conditioned to 195 KV successfully conditioned to 195 KV → ONLY available until August 2004 for MEG → ONLY available until August 2004 for MEG New Vertical Separator New Vertical Separator approved for MEG approved for MEG Originally So-called copy of LEMs separator Originally So-called copy of LEMs separator modified design underway & HV-parts ordered modified design underway & HV-parts ordered or delivered or delivered V max 200 KV V max 200 KV D plates 18 cm D plates 18 cm L eff 70 cm L eff 70 cm  Expected End 2004 !!!  Expected End 2004 !!! V max 200 KV V max 200 KV D plates 18 cm L eff 70 cm

11. P.-R. KettleMEG-Review July 200411 Current Component Status – Triplet II Old Triplet II New Triplet II: Finished - LEMs magnets shorter version of old Triplet II using 3 QSK quadrupole magnets using 3 QSK quadrupole magnets …better …better New Triplet II: Finished - LEMs magnets shorter version of old Triplet II using 3 QSK quadrupole magnets using 3 QSK quadrupole magnets …better …better Presently in storage Presently in storage → will be implemented during → will be implemented during Phase I Commissioning 23rd June – Mid August 2004 Phase I Commissioning 23rd June – Mid August 2004

12. P.-R. KettleMEG-Review July 200412 Current Component Status – BTS Beam Transport Solenoid BTS: Beam Transport Solenoid BTS:  Design Problems SOLVED  Design Parameters submitted Novosibirsk (mid April) detailed design underway  Contract end June  Design, testing + manufacture 9 months (end March 2005)  Waiting for other tenders at present Beam Transport Solenoid BTS: Beam Transport Solenoid BTS:  Design Problems SOLVED  Design Parameters submitted Novosibirsk (mid April) detailed design underway  Contract end June  Design, testing + manufacture 9 months (end March 2005)  Waiting for other tenders at present BTS COBRA Full simulations performed with GEANT (from colli. System to target in COBRA) Part simulations done with Graphics TRANSPORT & TURTLE, ANSYS & TRACK → input measured beam phase space from test beam results → all major parameters studied Conclusion: beam spot-size   5mm at target not possible without loss of rate !!! beam spot-size   5mm at target not possible without loss of rate !!! Possible consequences for experiment? Possible consequences for experiment?Conclusion: beam spot-size   5mm at target not possible without loss of rate !!! beam spot-size   5mm at target not possible without loss of rate !!! Possible consequences for experiment? Possible consequences for experiment?

13. P.-R. KettleMEG-Review July 200413 BTS continued Sep Trip I Trip II ASC BTS COBRA X Y TRANSPORT Optics ( BTS COBRA optics only schematic here) Axial Field Coupling Centre COBRA → Centre BTS COBRA BTS Summed ++ Summed +- Various Excitations + Coupling Schemes tested SNM, DNM, Reversed Field, Compensation SNM, DNM, Reversed Field, Compensation so Final Solution → Maximum Flexibility so Final Solution → Maximum Flexibility Single Node Double Node

14. P.-R. KettleMEG-Review July 200414 Current Component Status – BTS cont. Summary of Main Results (same Polarity solenoids) Summary of Main Results (same Polarity solenoids) No Degrader, No vacuum Window, No He → spot-size  ~ 5mm No Degrader, No vacuum Window, No He → spot-size  ~ 5mm He Only → spot-size 25 % larger He Only → spot-size 25 % larger Full Degrader in BTS all materials → spot-size  ~ 15mm Full Degrader in BTS all materials → spot-size  ~ 15mm Degrader Intermediate focus inside COBRA → spot-size  ~ 10mm Degrader Intermediate focus inside COBRA → spot-size  ~ 10mm (potential background source) (potential background source) Split Degrader BTS + intermediate focus → spot-size  ~ 13mm Split Degrader BTS + intermediate focus → spot-size  ~ 13mm Beam-spot Size Beam-spot Size  Divergence & Multiple scattering + lever-arm IMPORTANT!!!  Divergence & Multiple scattering + lever-arm IMPORTANT!!!  He less important  He less important Radial + Axial Focussing Radial + Axial Focussing  depends on: Beam Divergence & Fringe Field of Solenoids  depends on: Beam Divergence & Fringe Field of Solenoids Radial component & hence focussing Enhanced by opposite polarity fields!!! BTS reverse polarity wrt Compensation Coils + COBRA BTS reverse polarity wrt Compensation Coils + COBRA  Spot-size reduced 30 % compared with same polarity !!!  Spot-size reduced 30 % compared with same polarity !!!

15. P.-R. KettleMEG-Review July 200415 Current Component Status – BTS cont. DNM Reverse Field Sol n BTS COBRA BTS COBRA  P ~ 6 MeV/c  P ~ 4 MeV/c Radial RadialFocussing Defocusing Like polarity Reverse polarity  10 mm

16. P.-R. KettleMEG-Review July 200416 Current Component Status – BTS cont. BTS Sol n : DNM Reversed Field DNM & SNM Like Polarity allowed by final Specs Degrader No loss 12% He loss 12% He loss 3% Decays 3% Decays Transmission Profile (no Target) BTS  TRANS  98% BTS-COBRA  TRANS = 85% Confirmed in Test Beam 88% µ + stopped in 400µ CH 2 Tg 88% µ + stopped in 400µ CH 2 Tg 86% He He 240µ CH 2 eq R stops = R µ ·  TRANS ·  STOP R µ = 8.5·10 7 µ + s -1 at 1.8 mA 4cm Tg  TRANS = 0.85,  STOPS = 0.88 R stops = R µ ·  TRANS ·  STOP R µ = 8.5·10 7 µ + s -1 at 1.8 mA 4cm Tg  TRANS = 0.85,  STOPS = 0.88 (Stop Rate) R Stops = 6.4·10 7 µ + s -1 at 1.8 mA 4cm Tg (want 2.5·10 7 s -1 for sensitivity) (1.1·10 8 µ + s -1 at 1.8 mA 6cm Tg (1.1·10 8 µ + s -1 at 1.8 mA 6cm Tg

17. P.-R. KettleMEG-Review July 200417 Current Component Status – BTS cont. Beam-spot Size Reduction Necessary? → 10 mm probably OK from TC, DC simulations Necessary? → 10 mm probably OK from TC, DC simulations Without rate-loss → very Difficult (sub-surface μ + ?) Without rate-loss → very Difficult (sub-surface μ + ?) Use Smaller Target → He Problem (240 μ CH 2 Eq.) missed μ + Stop at downstream end of Use Smaller Target → He Problem (240 μ CH 2 Eq.) missed μ + Stop at downstream end of COBRA e + background or annihilation 511 keV  s can one distinguish point-of-origin of background? If so maybe OK COBRA e + background or annihilation 511 keV  s can one distinguish point-of-origin of background? If so maybe OK  Conclusion: use collimators inside BTS to restrict divergence  Conclusion: use collimators inside BTS to restrict divergence  BTS specifications fixed won’t change Spot-size  Still time to optimize collimator/degrader layout

18. P.-R. KettleMEG-Review July 200418 Current Component Status – BTS cont. BTS Final Specifications Machine Drawings in preparation at Novosibirsk at Novosibirsk 2800 mm 380 mm 460 mm 300 mm 2630 mm

19. P.-R. KettleMEG-Review July 2004 19 Effect of Beam Spot Size Simulations by: Wataru Ootani & Hajime Nishiguchi

20. MEG-Review July 200420 P.-R. Kettle Beam Spot Size In the current design of the beam line, it is difficult to make the beam spot size smaller than 10mm( σ ) without loss of beam rate. Although, it is possible to make it smaller by using collimator, further beam tuning, etc., it is useful to look into the effect of large beam spot on detector performance.

21. MEG-Review July 200421 P.-R. Kettle Effect on Timing Counter

22. MEG-Review July 200422 P.-R. Kettle Hit Distribution TC geometry:  Larger acceptance to cover most of events: 22.5cm<z<125cm,  28.5cm<r<29.0cm for φ-counter, 29.5cm<r<31.5cm for z-counter Beam spot size:  σ=0.5, 1.0, 1.5, 2.0cm

23. MEG-Review July 200423 P.-R. Kettle Efficiency Timing counter acceptance:  26cm<z<125cm, 0°<φ<360° Drift chamber materials are not taken into account. ~3% difference

24. MEG-Review July 200424 P.-R. Kettle Michel Positron Hit Rate ~5% difference

25. MEG-Review July 200425 P.-R. Kettle Trigger Rate TC filtering with e-γ direction match in 1st level trigger Suppression factor (= Φe/ΔΦe)  Φe: TC total angular acceptance =150°  ΔΦe: angle range corresponding to calorimeter angle resolution ΔΦγ =7° φrange φrange(ΔΦγ =7°)

26. MEG-Review July 200426 P.-R. Kettle Trigger Rate, cont’d Suppression factor Trigger rate (assuming 20Hz at σ=0.5cm)

27. MEG-Review July 200427 P.-R. Kettle Impact Time Spread Correlation bw/ time and z of impact point Impact time spread Should be corrected with reconstructed track-length intrinsic

28. MEG-Review July 200428 P.-R. Kettle Effect on Drift Chamber

29. MEG-Review July 200429 P.-R. Kettle Signal Positron Bending Diameter Projected bending diameter of signal positron

30. MEG-Review July 200430 P.-R. Kettle Efficiency Loss

31. MEG-Review July 200431 P.-R. Kettle Trigger Rate Change of count rate in possible trigger window ( bending diameter ±1σ,±2σ,±3σ). this counting rate is raw rate summed over whole DC system and doesn’t contain other trigger requirements from TC and Xenon. If used as 2 nd -Level Trigger Trigger If used as 2 nd -Level Trigger Trigger

32. MEG-Review July 200432 P.-R. Kettle Spot-size Summary Effects of larger beam spot size on performances of timing counter and drift chamber were investigated. No serious effect was found on both detectors for 10mm beam spot size.

33. P.-R. KettleMEG-Review July 200433 Summary/Conclusions Main problem with BTS/COBRA coupling solved Main problem with BTS/COBRA coupling solved BTS Specification submitted to Novosibirsk (mid-April) expected End BTS Specification submitted to Novosibirsk (mid-April) expected End March 2005 March 2005 Spot-size at Target expected to be larger than Proposal now  10 mm Spot-size at Target expected to be larger than Proposal now  10 mm not thought to be major problem (simulations TC, DC) not thought to be major problem (simulations TC, DC) Expected Stop-rate R Stops = 6.4·10 7 µ + s -1 at 1.8 mA 4cm Tg Expected Stop-rate R Stops = 6.4·10 7 µ + s -1 at 1.8 mA 4cm Tg (1.1·10 8 µ + s -1 at 1.8 mA 6cm Tg) (1.1·10 8 µ + s -1 at 1.8 mA 6cm Tg) From background & sensitivity want (2.5·10 7 μ + s -1 ) Triplet I & II Finished Triplet I & II Finished Separator II ready for testing (new HV power supply) Separator II ready for testing (new HV power supply) New vertical Separator expected end 2004 New vertical Separator expected end 2004 Target + He Bag Design next Target + He Bag Design next Beam Line Commissioning Started, initial results reproduced so far!!! Beam Line Commissioning Started, initial results reproduced so far!!!  -beam will also be studied  -beam will also be studied Main problem with BTS/COBRA coupling solved Main problem with BTS/COBRA coupling solved BTS Specification submitted to Novosibirsk (mid-April) expected End BTS Specification submitted to Novosibirsk (mid-April) expected End March 2005 March 2005 Spot-size at Target expected to be larger than Proposal now  10 mm Spot-size at Target expected to be larger than Proposal now  10 mm not thought to be major problem (simulations TC, DC) not thought to be major problem (simulations TC, DC) Expected Stop-rate R Stops = 6.4·10 7 µ + s -1 at 1.8 mA 4cm Tg Expected Stop-rate R Stops = 6.4·10 7 µ + s -1 at 1.8 mA 4cm Tg (1.1·10 8 µ + s -1 at 1.8 mA 6cm Tg) (1.1·10 8 µ + s -1 at 1.8 mA 6cm Tg) From background & sensitivity want (2.5·10 7 μ + s -1 ) Triplet I & II Finished Triplet I & II Finished Separator II ready for testing (new HV power supply) Separator II ready for testing (new HV power supply) New vertical Separator expected end 2004 New vertical Separator expected end 2004 Target + He Bag Design next Target + He Bag Design next Beam Line Commissioning Started, initial results reproduced so far!!! Beam Line Commissioning Started, initial results reproduced so far!!!  -beam will also be studied  -beam will also be studied

34. P.-R. KettleMEG-Review July 200434 MEG Beam Commissioning Schedule MEG Beam Commissioning Schedule Part 1 Part 2 Part 3

35. P.-R. KettleMEG-Review July 200435 Schedule Beam Line 2002200320042005 Test Milestone AssemblyDesignManufactoring Studies Solenoid BTS Triplet I + II Target Part 1Part 2 New Separator Part 3 Beam Line Commissioning Sep+BTS+COBRACOBRA+Target GottaPrak.Gotta ? Studies Solenoid BTS Triplet I + II Target Part 1 New Separator Part 2 Beam Line Commissioning Pi beam? Platform