# Presentation: 295154

## MARS15 simulations of the MERIT Mercury Target Experiment 

- Fermilab
- March 18, 2008

_**2008 Neutrino Factory and Muon Collider Collaboration meeting**_

- Sergei Striganov
- Fermilab

## OUTLINE

- Introduction
- Geometry& beam description
- Activation, doses, fluxes
- Energy deposition in detectors
- Energy deposition in target

## 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.

## MARS code

-    MARS code system is a set of Monte Carlo programs for detailed simulation of hadronic and electromagnetic cascades in an arbitrary geometry of accelerator, detector and spacecraft components with particle energy ranging from a fraction of an electron volt up to 100 TeV. The original version of the MARS code was created by Nikolai Mokhov in 1974 and is developed since then
-    in IHEP (Protvino), SSCL and Fermilab.

## MERIT geometry in MARS

## MERIT geometry in MARS

## MERIT geometry in MARS

## Beam description 

- Courant-Snyder parameters - vertical direction:
- αv  = 0.26
- βv  = 279 cm
- σv  = 0.117 cm
- Courant –Snyder parameter -horizontal direction:
- αh = 0.53
- βh = 279 cm
- σh = 0.129 cm
- Momentum distribution:
- σp= 480 MeV/c

- 2.5 mm

## 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

## Absobed dose in Gy per 3 1015 protons

- Acceptable level for electronic devices

- Acceptable level for electronic devices

## Radiation levels in detector elements

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

## Particle production in MARS at 24 GeV/c

## Detector positions and charged hadron flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Detector positions and charged hadron flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Electron/positron flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Gamma flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Energy spectra ( 12 degree detector). Blue lines – all particles, red lines- particles created in attenuator

## Time distributions in 12 degree detector

## Energy depositions in detectors for 15 Tesla field

- pCVD diamond detectors were chosen to measure secondary particle production. Charged particles create electron-hole pair in a voltage biased diamond, inducing a current in the circuit. Energy to create one electron-hole pair is about 14 eV. Detector area is 7.5x7.5 mm, thickness – 0.5 mm.

## Energy depositions in detectors for different magnetic field in solenoid

- Detector 1: -90 degree
- Detector 2: -45 degree
- Detector 3: -22 degree
- Detector 4: -10 degree
- Detector 5: -7.5 degree
- Detector 6: -4.7 degree
- Detector 7:  4.7 degree
- Detector 8:  7.5 degree
- Detector 9:  10 degree
- Detector 10: 45 degree
- Detector 11: 90 degree
- Detector 12:  9 degree
- Detector 13:  0 degree

## Energy depositions in detectors for different beam position at the target

## Detector positions in experiment

## Charged particle flux [cm-2] – Hg out

## Charged particle flux [cm-2] – Hg in

- Charged particle flux [cm-2] – Hg in

## Energy deposition in Hg jet

- 15 Tesla

- No field

- beam

- beam

## Energy deposition in Hg jet at 24 GeV/c15 Tesla, circle

- 5x5 mm

- beam

## Energy deposition in Hg jet at 24 GeV/c, 0 and 15 Tesla, circle

- 0 Tesla

- 15 Tesla

## Energy deposition in Hg jet at 24 GeV/c15 Tesla, ellipse

- 12x2 mm

## Energy deposition in Hg jet at 24 GeV/c0 and 15 Tesla, ellipse

- 0 Tesla

- 15 Tesla

## Energy deposition in Hg jet 

- Energy deposition density in Hg    target was calculated for MERIT momenta 14 and 24 GeV/c (3x1013 proton/pulse) and new muon collider baseline 56 GeV/c (4 x1013 proton/pulse) for circular and elliptical shapes. Beam spot size on target had radial rms of 1.6 mm
- Peak energy deposition densities (15T, 5x5 mm) are 125, 182, 655 J/g/pulse
- Total energy depositions in jet (15T, 5x5 mm)
- are 6.7, 12 and 46 kJ/pulse
- Total energy deposition is about 30% higher at 15 Tesla than at 0 Tesla for circular and elliptical jets
- Peak energy deposition in elliptical target is practically independent of magnetic field value
- Peak energy deposition in cylindrical jet is about 15% higher at 15 Tesla than
- at 0 Tesla

## Backup slides

## Neutron flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Muon flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Proton flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Charged pion/kaon flux (1/cm2 per 3 1013 protons on target)

- 15 Tesla

- No magnetic field

## Energy deposition in detectors. No target.

- Detector 1: -90 degree
- Detector 2: -45 degree
- Detector 3: -22 degree
- Detector 4: -10 degree
- Detector 5: -7.5 degree
- Detector 6: -4.7 degree
- Detector 7:  4.7 degree
- Detector 8:  7.5 degree
- Detector 9:  10 degree
- Detector 10: 45 degree
- Detector 11: 90 degree
- Detector 12:  9 degree
- Detector 13:  0 degree

## 24 GeV/c – Hg out

## 24 GeV/c – Hg in