Recent Studies on ILC BDS and MERIT

S. Striganov

APD meeting, January 24

Muon background from ILC BDS

Halo interacts with thin primary spoilers and produces electrons and photons

Electons and gammas hit thick secondary collimators

Electromagnetic shower produce muons – about

5 10-5 muon/lost electron Muon background can be

reduced about 2000 by using two magnetized spoilers

New tunnel geometry

Magnetized wall

Concrete wall and doughnuts

Condition

6.5 m radius

detector

1 bunch

2.5 m radius

TPC

200 bunches

2.0 m radius

TPC

160 bunches

5 m long magnetized wall

fills tunnel at 349 m,

2m concrete wall – MARS

13 (3) 387 (152) 192 (74)

11, 4 m long “doughnuts”

same polarity,

1 m unmagnetized wall – Lew, 2m concrete wall – MARS

8 (9.6)

(all same sign)

847 (1268)

(all same sign)

448 (646)

(all same sign)

11, 4 m long “doughnuts”

alternating polarity,

1 m unmagnetized wall

5 538 290

Summary TableNumber of Muons in Detector for Three Shielding Conditions Push-pull IR, 500 GeV CM, BDS 2006c Black numbers – Keller, red numbers - MARS

* Collimate 0.1% halo, muons from both beams

October 24, 2006

Keller v.s. MARS

• Halo distribution: MARS and Keller – from STRUCT• Interactions with primary collimator: MARS – internal

routine, Keller – TURTLE (electron/positron only, no photon transport)

• Interaction with secondary collimator: MARS – internal routine, Keller – approximation of shower

• Muon production: MARS and Keller – based on same model

• Muon transport: MARS – internal routine, Keller uses MUCARLO – no fluctuation of energy loss, simplified multiple Coulomb scattering

Source

• TURTLE does not transport photons – there are no photons (about 60% of total energy) produced on primary collimator in Keller simulations. All photon energy goes to electrons/positrons.

• Secondary electrons/positrons and gammas produced in MARS calculations agree well with STRUCT.

Geometry update

Detailed comparizon

Conclusions• Acceptable agreement

between Keller and MARS calculations in collimation section

• Large differences in bending sections

• Zeuthen package based on GEANT3 gave 2-3 times more muons than MUCARLO (TESLA, 1994)

Target for muon collider

MERIT experiment The MERIT experiment, to be

run at CERN in 2007, is a proof-of-principle test for a target system that converts a 4-MW proton beam into a high-intensity muon beam for either a neutrino factory complex or a muon collider. The target system is based on a free mercury jet that intercepts an intense proton beam inside a 15-T solenoidal magnetic. The Hg jet delivery system will generate a 1-cm diameter

mercury stream with velocities up to 20 m/s.

MERIT geometry in MARS

MERIT geometry in MARS

Simulations tasks Particle fluxes, energy

deposition, absorbed doses and residual activities in experimental hall

Absorbed dose and activation of mercury vapor analyzer

Activation of hydraulic fluid

Activation of mercury vapor filter

Secondary particles production

Radiation levels

Absorbed dose in Gy/3 1015 protons 30day/1day residual activity in mSv/h

Radiation levels in detector elements

• Absorbed dose in mercury vapor analyzer is 630 Gy (top) and 14 Gy (back). Acceptable level is 50-100 Gy.

• Residual dose rate on contact after 5 day of irradiation and 1 hour of cooling: mercury vapor analyzer – 0.17 mSv/hr (top), 0.007 mSv/hr (back), hydraulic fluid – 0.021 mSv/hr, mercury vapor filter -0.18 mSv/hr.

Acceptable level is about 1 mSv/hr at FNAL, 0.1(?) mSv/hr

at CERN

Detector positions and particle fluxes per pulse (3 1013 protons).

charged hadrons (E>200 keV)

neutrons (E>100 keV)

Detector positions and particle fluxes per pulse (3 1013 protons).

electrons (E>200 keV) gammas (E>200 keV)

Energy spectra ( 0 degree detector). Blue lines – all particles, red lines- particles created in attenuator.

Time distributions in 0 degree detector

Energy spectra ( 6.7 degree detector). Blue lines – all particles, red lines- particles created in attenuator.

Energy spectra ( 11.5 degree detector). Blue lines – all particles, red lines- particles created in attenuator.

Energy spectra ( 45 degree detector). Blue lines – all particles, red lines- particles created in attenuator.

Time distribution in 45 degree detector