Thomas Roser Snowmass 2001 June 30 - July 21, MW AGS proton driver (M.J. Brennan, I. Marneris, T. Roser, A.G. Ruggiero, D. Trbojevic, N. Tsoupas, S.Y. Zhang) Parameters and layout Beam loss considerations 1.2 GeV Superconducting Linac 2.5 Hz AGS power supply and rf system 4 MW Upgrade Bunch compressor ring Cost estimate

AGS proton driver parameters 1 MW AGSAGS presently Total beam power [MW] Beam energy [GeV]2424 Average current [  A]426 Cycle time [ms] No. of protons per fill1  ( )  Average circulating current [A] No. of bunches per fill66 No. of protons per bunch1.7  ~ 1  Time between extracted bunches [ms]20 33 Rms bunch length [ns]330 Peak bunch current [A]40030 Total bunch area [eVs]5 15 Rms bunch emittance [eVs] Rms momentum spread

AGS proton driver layout AGS 1.2 GeV  24 GeV 0.4 s cycle time (2.5 Hz) 116 MeV Drift Tube Linac (first sections of 200 MeV Linac) BOOSTER High Intensity Source plus RFQ Superconducting Linacs To RHIC 400 MeV 800 MeV 1.2 GeV 0.15 s0.1 s0.15 s To Target Station

Beam loss at H - injection energy AGS BoosterPSRSNS1 MW AGS Beam power, Linac exit, kW Kinetic Energy, MeV Number of Protons N P, Vertical Acceptance A,   m  2  N P /  2  3 A),   m Total Beam Losses, % Total Loss Power, W Circumference, m Loss Power per Meter, W/m

Beam losses in AGS Major loss points Present AGS 1 MW AGS % particlesBeam power% particlesBeam power Injection and early accel.: Controlled3.0 %1.5 kW Uncontrolled30 %1.9 kW0.3 %0.2 kW Transition 2.0 %0.4 kW1.0 %2.9 kW Total:2.3 kW4.6 kW l Injection modeled after SNS but much lower repetition rate and less foil traversals  Allow 30 times more beam loss l Transition losses are presently dominated by beam momentum spread required for AGS injection stacking. Direct injection should eliminate chromatic transition losses. l 4.6 kW should be acceptable for hand maintenance.

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

1.2 GeV Superconducting Linac Beam energy  0.4 GeV0.4  0.8 GeV0.8  1.2 GeV Rf frequency805 MHz1610 MHz1610 MHz Accelerating gradient11.9 MeV/m22.0 MeV/m21.5 MeV/m Length75.4 m43.9 m42.6 m Beam power, linac exit17 kW34 kW50 kW

New AGS main magnet power supply presently: l Repetition rate2.5 Hz1 Hz l Peak power110 MW 50 MW l Average power4 MW 4 MW l Peak current4.2 kA 5 kA l Peak total voltage  25 kV  10 kV l Number of power converters / feeds62

Distribution of current feeds

AGS rf system upgrade Use present cavities with upgraded power supplies (two 300 kW tetrodes/cavity) presently: Rf voltage/turn1 MV0.4 MV harmonic number Rf frequency~ 9 MHz MHz Rf peak power3 MW Rf magnetic field18 mT

Bunch merging and compression 80 ns h = eVs/bunch Adiabatic merging: h = kV/turn ~ 5 eVs/bunch h = 24 1 MV/turn Adiabatic quad pumping: 15 ns (3 ns rms)

Phased AGS intensity upgrade present AGS0.4 MW AGS 1 MW AGS SC LinacNoYesYes AGS PS upgradeNoNoYes Total beam power [MW] Beam energy [GeV] Average current [  A] Cycle time [ms] No. of protons per fill0.7    Average circulating current [A] No. of bunches at extraction66 6 No. of protons per bunch~ 1    Total bunch area [eVs]1555 Time betw. extr. bunches [ms]332020

Towards 4 MW Upgrade IUpgrade IIUpgrade III Linac intensity/pulse1.2    Linac rep. rate2.5 Hz2.5 Hz5.0 Hz Linac extraction energy1.2 GeV1.5 GeV1.5 GeV  2  Beam power54 kW144 kW288 kW AGS intensity/pulse1.0    AGS rep. rate2.5 Hz2.5 Hz5.0 Hz* Rf peak power3 MW6 MW8 MW Rf gap volts/turn1 MV1 MV1.5 MV AGS extraction energy 24 GeV24 GeV24 GeV Beam power1 MW2 MW4 MW Bunch area5 eVs10 eVs10 eVs Compressor ringnoyesyes *Symmetric cycle (0.1 s up, 0.1 s down) without flattop.

4 MW AGS proton driver layout AGS 1.2 GeV  24 GeV 0.2 s cycle time (5 Hz) 116 MeV Drift Tube Linac (first sections of 200 MeV Linac) BOOSTER High Intensity Source plus RFQ Superconducting Linacs To RHIC 400 MeV 800 MeV 1.5 GeV 0.1 s To Target Station 24 GeV Superconducting Compressor Ring 24 GeV Superconducting Storage Ring

Compressor ring Small superconducting ring to compress a single 24 GeV, 10 eVs bunch to 3 ns rms length. Small size reduces space charge tune shift and gap volt requirements. l Circumference200 m l Energy24 GeV l Dipole field~ 4 Tesla l Packing factor60 % Transition gamma~ 40 (d   /d  < 4) l Momentum acceptance  5 % (FFAG type lattice?) l Rf frequency 6 MHz (h = 4) l Rf Voltage per turn200 kV l Bunch length compression (rms)20 ns  3 ns

Bunch compression