1. 1 The BNL Super Neutrino Beam Project W. T. Weng Brookhaven National Laboratory APS April Meeting ( T13 ) Tampa, Florida April 18, 2005

2. 2 OUTLINE A.AGS Operation with protons B.Super Neutrino Beam Facility (1MW) B.1. New 1.2 GeV SCL B.2. AGS System Upgrade B.3. Neutrino Beam Production C.Cost Estimate and Schedule D.Further Upgrade Possibilities E.Conclusion

3. 3 AGS Intensity History 1 MW AGS

4. 4 Transition Time to Restore HEP

5. 5 AGS high intensity/RHIC operation AGS high intensity operation when RHIC is at store. RHIC at store: presently ~ 85 hrs/week (50%), goal: ~ 100 hrs/week (60%) Au – Au: l Typical 4-hour store length determined by Intra-Beam-Scattering (IBS) l With future luminosity upgrade (RHIC II) 4-hour store length determined by “burn-off” l Minimum refilling time is 5 – 10 minutes, typically takes < 1 hour l Fast injector switching between RSVP and RHIC mode beneficial p – p: l Typical store length: 8 – 10 hours l Slower injector switching possible and necessary to ramp super-conducting AGS Siberian snake Only incremental costs for high intensity operation. High intensity and RHIC operations is very beneficial for equipment reliability and development of expertise.

6. 6 AGS Upgrade to 1 MW 200 MeV Drift Tube Linac BOOSTER High Intensity Source plus RFQ Superconducting Linacs To RHIC 400 MeV 800 MeV 1.2 GeV To Target Station AGS 1.2 GeV  28 GeV 0.4 s cycle time (2.5 Hz) 0.2 s 200 MeV l 1.2 GeV SCL extension for direct injection of 8.9  10 13 protons low beam loss at injection; high repetition rate possible. l 2.5 Hz AGS repetition rate triple existing main magnet power supply and magnet current feeds, double rf power and accelerating gradient.

7. 7 Two Injection Schemes AGS presentAGS upgrade Kin. Energy28 GeV Rep. Rate1 / 3 Hz2.5 Hz Protons/ Cycle 0.67 x 10 14 0.89 x 10 14 Ave. Power0.10 MW1.0 MW 1.5-GeV Booster 200-MeV TDL 28-GeV AGS HI Tandem 1.2 GeV SCL 0.6 sec 2.4 sec AGS Booster 0.4 sec Typical DTL cycle for Protons 1 x 720 µs @ 30 mA

8. 8 AGS Proton Driver Parameters present AGS 1 MW AGS J-PARC Total beam power [MW]0.14 1.00 0.75 Injector Energy [GeV]1.5 1.2 3.0 Beam energy [GeV]24 28 50 Average current [  A]6 36 15 Cycle time [s]2 0.4 3.4 No. of protons per fill0.7  10 14 0.9  10 14 3.3  10 14 Ave. circulating current [A]4.2 5.0 12 No. of bunches at extraction6 23 8 No. of protons per bunch1  10 13 0.4  10 13 4  10 13 No. of protons per 10 7 sec.3.5  10 20 23  10 20 10  10 20

9. 9 Layout of the 1.2 GeV SCL

10. 10 1.2 GeV Superconducting Linac Beam energy 0.2  0.4 GeV0.4  0.8 GeV0.8  1.2 GeV Rf frequency805 MHz1610 MHz1610 MHz Accelerating gradient10.8 MeV/m23.5 MeV/m23.5 MeV/m Length37.8 m41.4 m38.3 m Beam power, linac exit17 kW34 kW50 kW Based on SNS Experiences

11. 11

12. 12 AGS Upgrade with CCL & SCL 200 MHz DTL BOOSTER High Intensity Source plus RFQ 800 MHz Superconducting Linac To RHIC 400 MeV 116 MeV 1.5 GeV To Target Station AGS 1.2 GeV - 28 GeV 0.4 s cycle time (2.5 Hz) 0.2 s l Add CCL from 116 MeV to 400 MeV l SCL from 400 MeV to 1.5 GeV at 25 MeV/m gradient l One type of cavity, cryomodule, and klystron, similar to SNS. 800 MHz CCL

13. 13 B.2. AGS System Upgrades 1. Beam Dynamics in the AGS n Injection Painting n Linac Emittance improvement n Transition Crossing n Ring Impedances n Beam Collimation and Shielding 2. AGS Magnet Test 3. New Power Supply Design 4. AGS RF Cavity Design

14. 14 Loss Limit & Estimate Losses

15. 15 Beam Loss at H - Injection Energy AGS BoosterPSR LANLSNS1 MW AGS Beam power, Linac exit, kW380100050 Kinetic Energy, MeV20080010001200 Number of Protons N P, 10 12 1531100100 Vertical Acceptance A,   m8914048055  2  3 0.574.506.759.56 N P /  2  3 A), 10 12   m0.2960.0490.0310.190 Total Beam Losses, %50.30.13 Total Loss Power, W15024010001440 Circumference, m20290248807 Loss Power per Meter, W/m0.82.74.01.8 ( Contro & Uncontrol )

16. 16 AGS Injection Simulation Injection parameters: Injection turns360 Repetition rate2.5 Hz Pulse length1.08 ms Chopping rate0.65 Linac average/peak current20 / 30 mA Momentum spread  0.15 % Inj. beam emittance (95 %)  m RF voltage450 kV Bunch length85 ns Longitudinal emittance1.2 eVs Momentum spread  0.48 % Circ. beam emittance (95 %) 100  m

17. 17 Halo in AGS as Function of Linac Emittance For acceptable operation, the linac emittance has to be less than 1.5 

18. 18 Linac Emittance Improvement Emittance at source 0.4 pi mm mr (rms,nor)

19. 19 AGS New Transition Crossing RF system: h=6 -> h=24; (+) High acceleration rate: dB/dt increased from 2.2 to 7.2 T/s (-) A large momentum spread is an issue – a result of the high RF voltage and large bunch area Tolerable beam loss is about 0.25% at transition The initial 95% bunch area needs to be reduced below 0.8 eVs

20. 20 Expected transition loss vs. bunch area

21. 21 New AGS Main Magnet Power Supply presently: l Repetition rate2.5 Hz1 Hz l Peak power 130 MW 50 MW l Average power2.7 MW (FEB)4 MW (SEB) l Peak current5 kA 5 kA l Peak total voltage  25 kV  10 kV l Number of power converters / feeds62

22. 22 Eddy Current Losses in AGS Magnets For 2.5 (5.0) Hz: In pipe: 65 (260) W/m In coil: 225 (900) W/m

23. 23 AGS RF System Upgrade Use present cavities with upgraded power supplies UpgradePresent Rf voltage/turn 1.0 MV 0.4 MV RF voltage/gap 25 KV 10 KV Harmonic number 24 6 (12) Rf frequency 9 MHz 3 (4.5) MHz Rf peak power 2.7 MW 0.75 MW Rf magnetic field18 mT 18 mT 300 kW tetrodes/cavity 2 1 AGS/RHIC Operation Pulse-to-Pulse Same RF System modulation

24. 24 B.3 Neutrino Beam Production 1 MW He gas-cooled Carbon- carbon target New horn design Target Hill for Radiation Protection Target on 11.3 degree down-hill slope to aim at Homestake mine Beam dump well above ground water table to avoid activation Near Detector Beam Monitoring

25. 25 Transient temperatures in the CC target subjected to a 100 TP, 28GeV 2mm RMS beam. Coolant temperature in the annular space T he = 5 degree C

26. 26 E951 Results: ATJ Graphite vs. Carbon-Carbon Composite The results demonstrate the superiority of CC in responding to Beam SHOCK. The question is: Will it maintain this key feature under irradiation ??? We will find out in the course of this irradiation phase

27. 27 Super-Invar Irradiation Study – CTE assessment Super-Invar

28. 28 PHASE-II TARGET MATERIAL STUDY WHAT’S NEXT ? PERFORM irradiation and assess mechanical property changes for a host of baseline materials. Perform more sophisticated assessment Carbon-Carbon composite This low-Z composite gives the indication that it can minimize the thermal shock and survive high intensity pulses. Because of its premise it is the baseline target material for the BNL neutrino superbeam initiative. The way its key properties (such as CTE or strength) degrade with radiation is unknown. Titanium Ti-6Al-4V alloy The evaluation of the fracture toughness changes due to irradiation is of interest regarding this alloy that combines good tensile strength and relatively low CTE Toyota “Gum Metal” This alloy with the ultra-low elastic modulus, high strength, super-elastic like nature and near-zero linear expansion coefficient for the temperature range -200 o C to +250 o C to be assessed for irradiation effects on these properties. VASCOMAX This very high strength alloy that can serve as high-Z target to be evaluated for effects of irradiation on CTE, fracture toughness and ductility loss AlBeMet A low-Z composite that combines good properties of Be and Al. Effects of irradiation on CTE and mechanical properties need to be assessed TG-43 Graphite Possibly Nickel-plated Aluminum T6061 (Horn material) for visible irradiation/corrosion effects, loss of electrical conductivity, delamination, etc.

29. 29 WHAT IS OF INTEREST TO US IN POST-IRRADIATION PHASE Resilience in terms of strength/shock absorption CTE evaluation Stress-strain Fatigue Fracture Toughness and crack development/propagation Corrosion Resistance De-lamination (if a composite such as CC or plated HORN conductor) – Use of ultrasonic technology to assess changes Resistivity changes All of the above can/will be done in Hot Cell. Other tests are also in the planning for scrutiny of the successful candidates (laser induced shock and property measurements)

30. 30 Super Neutrino Beam Geographical Layout  BNL can provide a 1 MW capable Super Neutrino Beam  the neutrino beam can aim at any site in the western U.S.; the Homestake Mine is shown here  there will be no environmental issues if the beam is produced atop the hill illustrated here and the beam dumped well above the local water table  construction of the Super Neutrino Beam is essentially de-coupled from AGS and RHIC operations Super Neutrino Beam Geographical Layout

31. 31 Neutrino Spectrum at 1 km Low Z (Carbon) target seems feasible for 1 MW, 28 GeV proton beam. Thin low Z target minimizes reabsorption which increases flux of high energy neutrinos

32. 32 BNL  Homestake Long Baseline Neutrino Beam 2540 km Homestake BNL 28 GeV protons from the AGS 1 MW beam power from upgraded proton driver 500 kTon Water Cherenkov Detector Conventional Horn Focused beam Baseline Design: Alternate detector sites such as the WIPP facility in New Mexico and the Henderson mine in Colorado would be acceptable. The Homestake site is used for purposes of calculation.

33. 33 Preliminary Cost Estimate – Continued Total Direct Cost = $274 M Add: Contingency, 30% BNL Project Overhead, 14.5% Total Estimated Cost = $407 M

34. 34 Construction Schedule FY 12345678910 R&D Construction Commissioning Research

35. 35 D. Further Upgrade Possibilities Several possible upgrades, if combined, can provide 2 MW beam. a. Increase the AGS repetition rate beyond 2.5 Hz. This can be accomplished by ramp down the AGS magnet in 0.1 sec, a combined rep rate of 3.3 Hz. a. Increase the AGS intensity to 1.3 x 10 14 protons per pulse. To make this option possible, the SCL energy has to be increased to be 1.5 GeV. A better transition crossing system has also to be implemented. b. A longer decay tunnel for capturing neutrino beam. c. An improved hardonic beam focusing system

36. 36 E. Conclusions 1.The feasibility has been demonstrated for a 1MW upgrade for the AGS 2.It is possible to further upgrade the AGS to 2 MW 3.Active R&D efforts are in progress to improve on the design and reduce cost. 4.The Total Estimated Cost is 407 M$ to complete the AGS upgrade and neutrino beam delivery system. 5.The construction can be completed in 5 years, with several years R&D efforts.