1 Short pulse neutron source Pulse length 1

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1 - Short pulse neutron source Pulse length: ~ 1 s Repetition rate: 50

1 - Short pulse neutron source Pulse length: ~ 1 s Repetition rate: 50 – 60 Hz Average beam power: ~ 1. 5 MW Beam energy: 1 – 8 Ge. V Particle type: protons or H- Spallation Neutron Source (ORNL)

Overview 3 Me. V H- source LEBT RFQ MEBT 90 Me. V DTL 200

Overview 3 Me. V H- source LEBT RFQ MEBT 90 Me. V DTL 200 Me. V CCL 1 Ge. V SCL HEBT Storage Ring 352. 2 MHz 15 m 704. 4 MHz 400 m Target Wf = 1 Ge. V, If = 1. 5 m. A (average), then P = 1. 5 MW. Average ion source current estimated to be Is = 2 -2. 5 m. A (in order to account for transverse and longitudinal losses along the LINAC, as well as chopped portions of the beam). Repetition rate = 50 Hz, Duty Factor = 6%, then Is = 33 -42 m. A (peak).

WARM PART OF THE LINAC (H-) Ion source (3 solenoids) 50 ke. V LEBT

WARM PART OF THE LINAC (H-) Ion source (3 solenoids) 50 ke. V LEBT 5 m 3 m (Álvarez, 6 tanks, 352 MHz) (4 -vane, 352 MHz) 50 ke. V RFQ 3 Me. V 4 m 4 m CCL 90 Me. V 40 m MEBT (4 modules, 704 MHz) DTL 3 Me. V (Quads, rebuncher, chopper) SCL 200 Me. V 60 m Normalized transverse emittances estimated to grow from 0. 2 pi mm mrad (ion source) to less than 0. 5 pi mm mrad (end of warm linac).

RFQ OUTPUT ENERGY The power loss at energies above the neutron production threshold in

RFQ OUTPUT ENERGY The power loss at energies above the neutron production threshold in Cu (~2. 6 Me. V) is very low (ESS Bilbao RFQ design).

The superconducting Linac • Two kinds of cavities depending on the beam energy •

The superconducting Linac • Two kinds of cavities depending on the beam energy • b = 0. 6 cavities up to 400 Me. V • b = 0. 9 cavities for energy up to 1 Ge. V • Construction of about 10 medium beta cryomodules and 15 high beta cryomodules • Use of 15 bars He system for the 70 K thermal shield -> no need of LN 2 = only one coolant (helium) Saclay design of a 5 -cells high beta 704 MHz cavity Medium beta Saclay cavity withits helium tank and tuning system

Storage ring Beam rigidity: Magnetic field B = 0. 617 T → 8 Ge.

Storage ring Beam rigidity: Magnetic field B = 0. 617 T → 8 Ge. V 1 Ge. V Radius = 9. 168 m → Circumference Circ. = 57. 6 m Only dipoles! We need more space for other elements. Arc section: 90 m, Straight section: 90 m, Total circumference: 180 m Arc section Cells: 12 → Cell length: 7. 5 m, Dipoles/cell: 2 → Total dipoles: 24 angle = 360/24 = 15° Arc section - 3 FODO cells → dipole length = 2. 4 m sector dipole

FODO/Doublet

FODO/Doublet

k. D = -0. 589 m-2 k. F = 0. 573 m-2 FODO bx

k. D = -0. 589 m-2 k. F = 0. 573 m-2 FODO bx (max) = 12 m by (max) = 11 m D (max) = 3. 6 m D (rms) = 1. 4 m Qx = 5. 29 Qy = 5. 21 gtr = 3. 2 g 1 Ge. V = 2. 1 FODO/Doublet k. D = -0. 498 m-2 k. F = 0. 501 m-2 bx (max) = 45 m by (max) = 25 m D (max) = 3. 4 m D (rms) = 2. 7 m Qx = 3. 29 Qy = 3. 17 gtr = 3. 3 g 1 Ge. V = 2. 1

k. D = -0. 637 m-2 k. F = 0. 778 m-2 FODO/Doublet bx

k. D = -0. 637 m-2 k. F = 0. 778 m-2 FODO/Doublet bx (max) = 24 m by (max) = 17 m D (max) = 3. 8 m D (rms) = 1. 4 m Qx = 6. 29 Qy = 5. 22 gtr = 5. 1 g 1 Ge. V = 2. 1 Parameters of the storage ring at SNS: bx (max) = 16 m by (max) = 28 m D (max) = 4 m Qx = 6. 23 Qy = 6. 20 gtr = 5. 23

Many materials can be used: lead, tantalum, tungsten But mercury was chosen: • not

Many materials can be used: lead, tantalum, tungsten But mercury was chosen: • not damaged by radiation • high atomic number, making a source of numerous neutrons • liquid at room temperature -> dissipate the temperature rise better than a solid Proton beam 1 Ge. V: 35 Neutrons/Proton 8 Ge. V: 207 Neutrons/Proton