1. Meson Production Efficiencies
IDS Target Meeting
CERN
December 17, 2008

2. 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.

3. The Neutrino Factory Target Concept

4. 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.

5. 50GeV Beam-Mesons at 50m
40MeV<KE<180MeV

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

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

8. Step 1: Vary the Target Radius
Rmax=0.48cm

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

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

11. Optimized Target Parameters
Target Radius
Proton Beam Angle

12. Beam/Jet Crossing Angle

13. Meson Production Normalized to Beam Power

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

15. Compare 50m to Post-Cooling

16. 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

17. Backup Slides

18. Optimizing Soft-pion Production

19. Post-cooling 30π Acceptance