Helge Ravn CERN Muon week,

1
Target and Pion Collection System and Support
Facility

• CERN Target and Horn working group

CERN 10 May 2001
Http//cern.ch/Helge.Ravn/files/Muon week Talk
2
The E951 Collaboration
CERN Target and Horn working group
A. AUTIN, A. BALL, A. BERNADON, L. BRUNO, A.
FABICH, G. GRAWER, S. GILHARDONI, T. KURTYKA, J.
LETTRY, J.-M. MAUGAIN, H. RAVN, M. SILARI, P.
SIEVERS, N.VASSILOUPOULOS, V. VLACHOUDIS, H.
VINCKE and F. VOELKER
3
CERN reference scenario

• In order to produce 1021 neutrinos/year proton
  beams with a power of 1-4 MW needs to interact
  with a high Z target.

• Proton energy 2.2 GeV.
• Repetition rate 50 Hz
• Pulse duration 3.3 ms.
• Pulse intensity 1.5 1014/pulse
• Average beam power 4 MW
• Target absorbed power 1 MW
• Liquid Hg-jet target Diam. 10 mm
• Pion collection by means of a magnetic horn.

4
Heat load comparison

• Radioactivity laboratory and support facility
  similar to.
• EURISOL
• RIA
• ESS, SNS
• Nuclear waste transmutation

5
Thermal expansion waves in ISOLDE targets

• Splashes threshold (Pb, Sn and La targets 1993)
• 1?1013 protons per pulse, 20 bunches (h5)
• 0.5 ? 1012 protons per bunch (60ns, 1GeV)

ISOLDE target system
6
Thermal expansion wave and cavitation
7
Simulations
Surface evolution due to the interaction with
proton pulses
(R. Samulyak)
8
Why a Mercury-Jet

• High pion yield (high Z)
• High source brightness (high density)
• Flowing liquid have excellent power handling
  capabilities
• No water radiolysis
• Liquid at ambient temperature (no liquid-to-solid
  phase change issues)
• Minimal waste stream (compared to solid
  alternatives)
• Passive removal of decay heating
• No dominant long-lived radiotoxic products
• No confinement tubing (free flowing jet)
• No beam windows (differential pumping
  confinement)

9
Hg-jet system

• Power absorbed in Hg-jet 1 MW
• Operating pressure 100 Bar
• Flow rate 2 t/m
• Jet speed 30 m/s
• Jet diameter 10 mm
• Temperature- Inlet to target 30 C- Exit from
  target 100 C
• Total Hg inventory 10 t
• Pump power 50 kW

10
BNL CERN Trough test

• Perpendicular velocities of Hg-drops via high
  speed cameras (8000 frame/s, 25ms aperture and up
  to 1000 kframe/s, 0.15ms aperture)
• 0.5-4.0?1012 protons per bunch,
• Bunch length 100 ns
• Proton energy 26 GeV
• Results (preliminary)
• 6 to 75 m/s splashes measured (under atm.
  pressure)
• Scales with the number of protons in the bunch
• Questions
• Response to a multi-bunch pulse (CERN scenario)
• Response to a bunch length reduced to 3-5 ns
• Response to other dE/dx

11
BNL E-951 trough test8 kHz camera
1st P-bunch 1.8?1012 ppb 150 ns
Vsplash 20-40 m/s
Timing 0.0, 0.5, 1.6, 3.4 ms, shutter 25 ms
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BNL E-951 trough test 1MHz camera
Timing ms 0.0, 0.2, 0.4 0.6, 0.8, 1.0 shutter
150 ns
P-bunch 4.0?1012 ppb 150 ns
Vsplash 75 m/s
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BNL Hg-jet chamber

• P-bunch26 Gev,
• spot size r1.6x0.8 mm (rms),
• intensity lt4 1012 protons per bunch
• bunch length 150 ns
• Hg- jet diameter 1cm jet-velocity 3
  m/sprep. velocity 10 m/s

14
Jet test at BNL E-951 4 25th April 2001
Pictures timing ms 0.000 0.250 0.500 0.175 0.425
0.975 3.000
P-bunch 3.8?1012 ppb 100 ns to 0.45
ms Hg- jet diameter 1cm jet-velocity 3
m/s prep. velocity 10 m/s
15
Jet test at BNL E-951 1125th April 2001
Pictures timing ms 0.00 0.75 4.50 13.00
P-bunch 2.7?1012 ppb 150 ns to 0.45
ms Hg- jet diameter 1cm jet-velocity 3
m/s prep. velocity 5 m/s
16
Magnet field injection test 13T
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13T Magnet field map
Grenoble high magnetic field laboratory vertical
Solenoid Bmax13 T observed maximum gradient
dB/dz49.5 T/m pulsed mercury jet, d4mm, v4-15
m/s Measurements in 20 T field planned for Sept.
01
Mirrors
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Simulations
Surface evolution due to the interaction with
magnetic field
(R. Samulyak)
19
Comparison without/with magnetic field
- pictures taken with 0,1 ms shutter-speed (at
1000 fps) - all frames 48 ms after trigger of
valve
without field 0 T, v 4.6 m/s
with field
49.5 T/m, v 4 m/s
20
CERN Trough test
1/5 of the Neutrino factory beam power-densities
can be obtained in the 1.4 GeV BOOSTER/ISOLDE
p-beam
PSB-ISOLDE 3.2?1013 protons per pulse, 20,8,4
bunches (h5,2,1 ) Pulse length 2.4 ms (-20 ms
staggered extraction) Proton energy 1 GeV Trough
test at CERN Hg tight sealing 40 pulses.
Response to bunch up to 8?1013 ppB. Response to
beam size and beam energy. Disposal of Hg via
amalgams ?
21
CERN/ISOLDE In-Beam Experiment
- at ISOLDE Target Area
frontend
p beam
Hg container
camera
mirror
22
Nufact 140 bunches 1.15?1012
ppB bunch length 5 ns p-energy 2.2 GeV Pulse
duration 3.2 ms Pulse intensity 1.6?1014 ppp
velocities-pressure benchmarks for simulation
PSB-ISOLDE 4 bunches 8.0?1012 ppB bunch
length 200 ns p-energy 1,1.4 GeV Pulse
duration 3.2 ms Pulse intensity 3.2?1013 ppp
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Radiation safety of trough test
24
Magnetic Horn

• Units H40-400
• Type mm 40-400
• Waist radius mm 40
• Peak current in horn kA 300
• Total capacitance
• for 1 switching section µF 1453
• Duty cycle Hz 50
• Pulse duration
• (half period) µs 93
• Charging voltage V 6283
• Voltage on horn V 4200
• r.m.s. current in horn kA 14.5
• PH Mean power dissipation
• in horn by current kW 39.
• Water flow needed
• in l/min with ?? w 15C l/min 3power
  dissipation due to beam absorption to be added

25
Water-cooled granular target

• P. Sievers/CERN

Ta-Spheres, r 16.8 g/cm R 1mm Packing density
60 (140 spheres/cm3) R 10g/cm3 Small spheres
good for cooling surface/volume1.R Water
coolingv 6m/s through 20 of cross-section V
11l/s DT 18K (20 of 4MW, S. Gilardoni) DT
36K DP 4-5 Bar Re 104
26
Continuation of RD

• Test the Hg-jet in a 20 T magnetic field
• Systematic trough tests in the ISOLDE 1- 1.4 GeV
  proton beam
• Development of jet hydrodynamic models
• Improve the speed and hydrodynamic stability of
  the Hg-jet
• Building of a prototype horn and test heat
  transfer coefficient at the inner conductor and
  if possible the lifetime.
• Start preliminary engineering study of the
  integration of the plumbing of the target and the
  spent beam absorber in the horn.
• Design and build a continuos flowing Hg-jet set
  up for in-beam tests.
• Continue the study of alternative target concepts
  like radiation cooled solids and the water cooled
  granular target.