Meson Production Efficiencies IDS Target Meeting CERN December 17, 2008

Proton Driver Parameters Proton driver power: 4 MW Proton driver repetition rate: 50 Hz Proton energy: around 10 GeV 3 proton bunches in train 1.7×1013 protons per bunch at 10 GeV Bunch length 1–3 ns Train length at least 200 μs Repetition rate: stored energy in muon RF cavities is essentially thrown away. Higher rep rates, more energy thrown away, higher power requirements. May be challenging to get proton driver to rep higher anyhow. Proton energy: significant drop off in performance per unit power around 5 GeV, steady drop off at higher energies. Higher energies may be nicer for achieving short bunches (later) and reaching higher power (less charge required at low energy). But higher energy makes high rep rate harder, increases proton driver machine cost. Bunches in train: fed one at a time, separated by at least 17 μs (time to get through FFAG stage) to target. Less current per bunch, easier to get short bunches. More bunches means a longer storage ring: this requires digging deeper (water table issues), increased storage ring cost. Bunch length: performance flat to 1 ns, drops by about 7% at 3 ns. Train length: need to replace energy in accelerating cavities between passes. Input power into coupler is limited, thus one needs enough time between bunches to get the power in.

The Neutrino Factory Target Concept

The Target/Collection System Count all the pions and muons that cross the transverse plane at z=50m. For this analysis we select all pions and muons with 40 < KE< 180 MeV.

50GeV Beam-Mesons at 50m 40MeV<KE<180MeV

Mesons at 50m ISS Results reported April, 2006 Mesons/Proton Mesons/Proton normalized to beam power ISS Results reported April, 2006

Hg Jet Target Geometry Previous results: Radius 5mm, θbeam =67mrad Θcrossing = 33mrad

Step 1: Vary the Target Radius Rmax=0.48cm

Step 2: Vary the Beam Angle beam=89mrad

Step 3: Vary the Beam/Jet Crossing Angle crossing=25mrad

Optimized Target Parameters Target Radius Proton Beam Angle

Beam/Jet Crossing Angle

Meson Production Normalized to Beam Power

Process mesons through Cooling Consider mesons within acceptance of ε┴ = 30π mm and εL = 150π mm after cooling 180 MeV

Compare 50m to Post-Cooling

Summary At 20 GeV we have a 10% loss in efficiency Peak meson production efficiency for a Neutrino Factory Hg Target system occurs in the region of 6 to 10 GeV At 20 GeV we have a 10% loss in efficiency At 40 GeV we have a 20% loss in efficiency At 80 GeV we have a40% loss in efficiency

Backup Slides

Optimizing Soft-pion Production

Post-cooling 30π Acceptance