MDI Simulations at SLAC Takashi Maruyama, Lew Keller, Thomas Markiewicz, Uli Wienands, SLAC MAP Collaboration Meeting, FNAL June 21, 2013

2 Higgs Factory Simulation REVMOC Understand the lattice Find beam parameters along the lattice. - Tungsten discs with 5  aperture - Find launch parameters for Fluka Decay Turtle Decay electron hit rate near IP Power load Fluka Decay electron hit rate and power load to compare with Turtle. Machine background

3 Higgs Factory Muon Collider Lattice: Alexahin (preliminary) v8.2 2×10 12 muons/bunch Fill = 1000 turns = 1msec Fill frequency =30 Hz, 1 bunch/beam Muon decay rate = 5.1×10 6 /m/beam Gaussian beam 3 body unpolarized decay MDI shielding model, v2 Nozzle, 5/15/ cm-thick W discs with 5  elliptical aperture 5T detector solenoid One beam only in plots to be presented.

4 HF Geometry in Fluka

5 Detector Geometry in Fluka Detector geometry is also setup in Fluka. The machine background is calculated without the detector. Detector is not a shield, and we want to know pure machine background.

6 Beam envelope Launch Gaussian beam at z=22.5 m from IP. Tungsten discs with (5  x, 5  y ) elliptical apertures.

7 Decay Location for Hits in IR  beam Beampipe hits are mostly from decays within 8m of IP. May not depend on the machine lattice design.

8 Be beam pipe Hits FLUKA Energy (GeV) (incident) 4 W absorbed power

9 Upbeam Tungsten Cone FLUKA Energy (GeV) 1  C temp rise /fill at the tip of the nozzle (z= 90 cm) with no cooling

10 Downbeam Tungsten Cone FLUKA Energy (GeV)

11 Machine Background Score particles coming out of the nozzle and beampipe. Cut off energy - Photons: 100 keV (  1% in Si) - e+/e-: 10 MeV (  =0.7 cm in 5 Tesla) - Hadrons: 10 MeV - Neutrons: 10 MeV e- , e ,  , n (E, x, y, z, u, v, w)

12 Photons Photons/2cm/BX Z (cm) Time (ns) Energy (GeV) 590×10 6 /BX 80×10 6 /BX in t =75-80 ns From 1 st Downbeam W disc From Downbeam Nozzle T=0 ns when the muon is launched at z=22.5 m.

13 Photon hit density at R=1 m 1 m ILC photon hit density  1/cm 2 /BX Z (cm) Hits/cm 2 /BX No time cut T=75-80 ns

14 e+/e- e+/e-/2cm/BX Time (ns) Energy (GeV) 12×10 6 /BX 3×10 6 /BX in t=75-80 ns Z (cm)

15 Rmax distribution Nozzle Rmax x y Particles/2cm/BX ILC 500 GeV R (cm) T=75-80 ns

16 Neutrons Neutrons/10cm/BX Z (cm) Kin. Energy (MeV) Time (ns) 620k/BX 3k/BX in t=75-80 ns

17 +/-+/- Kin. Energy (GeV) Time (ns) Pions/10cm/BX Z (cm) 16k/BX 2k/BX in t=75-80 ns

18 Summary Decay electron hit rate and power load in the nozzle have been calculated. Electron hit rate in the Be beam pipe is 0.7×10 6 /BX. The power load in the nozzle is 2.7 kW. Machine background has been calculated using Fluka. All the numbers are still preliminary. Background can be passed to detector simulation. - (only 1/5100 of BX) Timing is very effective in reducing the detector background. Further studies are required for understanding the timing. Need to convolute the beam size  z  6 cm. e+/e- seems to be the most serious background. A large fraction of e+/e- are produced in the interactions near the IP and the timing cut is not effective.