autin

Funneling p’s and m’s: 

Funneling p’s and m’s Bruno Autin, Peter Sievers, André Verdier CERN François Méot CEA, Saclay

Proton Beam Parameters: 

Proton Beam Parameters

Why a funneling system?: 

Why a funneling system? No exotic and expensive technology. Lifetime in excess of one year. Evolutionary design.

How it works?: 

How it works? The proton beam is switched to 4 targets in sequence. Each of the 4 pion lines contains an integrated system of target, magnetic horn and cooling. The funnel is made of large aperture magnets with quadrupolar and pulsed dipolar coils.

Funneling step by step: 

Funneling step by step

Magnetic horn: 

Magnetic horn

Horn Parameters: 

Horn Parameters

Target in Horn : 

Target in Horn

Target dynamics 1: 

Target dynamics 1 Condition for shock Energy deposited in a time short wrt sound propagation time. Typical scales: Distance ~ 1 cm, vs ~ 3000 m/s, ts ~ 3 ms. Synchrotron: bunch length ~ 5 ns Accumulator: pulse length ~ 1 km ~ 3 ms. Escape from shock Fragment the target: Distance ~ 1 mm, ts ~ 0.3 ms. Good for accumulator. Insufficient for synchrotron.

Target dynamics 2: 

Target dynamics 2 Condition for rupture (P. Drumm et al., nFact00) Stress induced by shock exceeds elastic limit of target material. Typical scales: Ds ~ E a DT ~ 3500 MPa at 10 Hz in Ta Elastic limit ~ 400 MPa at room temperature. Escape from rupture No shock, no stress. Reduce DT by increasing repetition frequency and beam size.

Effect of funneling on target parameters: 

Effect of funneling on target parameters Ttarget THelium 1 target 4 targets

Pion Beam Parameters: 

Pion Beam Parameters

Polarities: 

Polarities Scheme 1: AC quadrupoles Scheme 2: DC quadrupoles Good transmission. Reduced transmission (2/3). Complicated power supplies due Conventional power supplies. to high stored magnetic energy.

Optical functions: 

Optical functions Center of mass trajectory b-functions

Magnet Parameters: 

Magnet Parameters

Muon production: 

Muon production Y = Nm/Np versus longitudinal emittance for : two transverse admittances et = 1p cm (no cooling), 4p cm (cooling) three regimes: solenoid, conventional and high field quadrupoles.

Conclusions: 

Conclusions Muon production for neutrino factories is on the way of being solved within the context of low energy, high repetition frequency proton driver. Target and horn developments have started but not at the wanted pace. Pending topics: magnet design, proton dump.