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Challenges and Progress on the SuperBeam Horn Design Marcos DRACOS IN2P3/CNRS Strasbourg NuFact 08 Valencia-Spain, June 30 - July 5 2008 Super-Beam Studies in Europe Super Proton Driver at CERN (SPL) Target and collector integration Hadron Collector Pulser Conclusion p p n

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challenges and progress on the superbeam horn design

Challenges and Progress on the SuperBeam Horn Design

Marcos DRACOS

IN2P3/CNRS Strasbourg

NuFact 08

Valencia-Spain, June 30 - July 5 2008

M. Dracos, NuFact08

super beam studies in europe

Super-Beam Studies in Europe

  • Super Proton Driver at CERN (SPL)
  • Target and collector integration
  • Hadron Collector
  • Pulser
  • Conclusion

M. Dracos, NuFact08

conventional neutrino beams

p

p

n

Conventional Neutrino Beams

proton beam

Decay tunnel

physics

hadrons

target

hadron collector

(focusing)

Detector

M. Dracos, NuFact08

spl super beam project
SPL Super-Beam Project

Accumulator

ring + bunch

compressor

H- linac 2.2, 3.5 or 5 GeV, 4 MW

p

proton driver

Magnetic

horn capture

(collector)

p

Target

hadrons

n, m

decay tunnel

~300 MeV nm beam to far detector

to be studied in EURO WP2

M. Dracos, NuFact08

super proton linac at cern

Super Proton Linac at CERN

SPL

(http://doc.cern.ch/yellowrep/2006/2006-006/full_document.pdf)

M. Dracos, NuFact08

spl cdr2 main characteristics

SPL (CDR2) main characteristics

butch compressor to go down to 3.2 s (important parameter for hadron collector pulsing system)

(possible energy upgrade to 5 GeV could be the subject of a 3rd CDR)

M. Dracos, NuFact08

proton target
Proton Target

very challenging task

  • 300-1000 J cm-3/pulse
  • Severe problems from : sudden heating, stress, activation
  • Safety issues !
  • Baseline for Super-Beam is solid target, mercury is optional (baseline for NF)
    • Extremely difficult problem : need to pursue two approaches :
      • Liquid metal target (Merit experiment)
      • Solid target (extensive R/D program at CCLRC and BNL)
  • Envisage alternative solutions

M. Dracos, NuFact08

proposed collection system
Proposed collection system

horn

proton beam

3.7 cm

8.5°

300 kA

4 cm

target

16.6 cm

40 cm

80 cm

taking into account the proton energy and collection efficiency, the target must be inside the horn

M. Dracos, NuFact08

proton target9

CC target

He OUT

He IN

fluidised jet of particles

some ideas

Proton Target

Proposed rotating tantalum target ring (realistic?)

Horn

Helium cooling of target

Liquid Mercury (MERIT)

Work at BNL and RAL

Experience on T2K target (750 kW) very useful

cooling is a main issue…

M. Dracos, NuFact08

hadron production
Hadron production

Particles coming out of the target

2.2 GeV protons

pT distribution not the same for all targets

the choice of the target could influence the hadron collection system (horn shape)

pT

From now on Hg will be considered

M. Dracos, NuFact08

hadron production uncertainties
Hadron production uncertainties

2.2 GeV protons

disagreement between models

(Monte Carlo production, interaction and transport codes)

p+ momentum

more development is needed (simulation, measurements)

M. Dracos, NuFact08

proton energy and pion spectra
Proton Energy and Pion Spectra
  • pions per proton on target.
  • Kinetic energy spectrum
    • 2.2 GeV:
      • <Ek>=300MeV
    • 3.5 GeV:
      • <Ek>=378MeV

interesting region for SPL SB

Ekine (GeV)

1GeV

2GeV

cos q

hadrons boosted forward

1

0

-1

M. Dracos, NuFact08

proposed design for spl
Proposed design for SPL

for pions coming out of the target

500 < pp < 700 MeV/c

p+ angle

p+ momentum

horn region

for a Hg target, 30 cm length, 15 mm (x1016/sec)

relatively better collection when pproton

the target must be inside the horn

M. Dracos, NuFact08

horn geometry
2.2 GeV proton beam :

<pp> = 405 MeV/c

<qp> = 60°

3.5 GeV proton beam :

<pp> = 492 MeV/c

<qp> = 55°

Horn geometry

I = 300 kAmp

I = 300 kAmp

r(m)

r(m)

B~1/r

B~1/r

B must be 0

B must be 0

4 cm

4 cm

target

target

30 cm

z(m)

30 cm

z(m)

M. Dracos, NuFact08

proposed design for spl15

600 kA

reflector

horn

proton beam

3.7 cm

8.5°

300 kA

4 cm

Hg target

16.6 cm

12.9°

20.3 cm

4 cm

40 cm

80 cm

70 cm

Proposed design for SPL

very high current inducing severe problems

M. Dracos, NuFact08

focusing power
Focusing Power

p- transverse momentum

p+ transverse momentum

(2.2 GeV option)

p- are deflected

20% more p+ with reflector

M. Dracos, NuFact08

present collectors
Present Collectors

In operation

(120 GeV)

In operation

(8 GeV)

completed

(12 GeV)

CERN horn prototype for SPL

Super-Beam

(3.5 GeV)

In operation

(400 GeV)

MiniBooNE

NUMI

CNGS

K2K

M. Dracos, NuFact08

decay tunnel
Decay Tunnel

Flux vs decay tunnel length

(2.2 GeV option)

short decay tunnel

M. Dracos, NuFact08

more about previous studies
More about previous studies
  • S. Gilardoni: Horn for Neutrino Factory and comparison with a solenoid
    • http://doc.cern.ch/archive/electronic/cern/preprints/thesis/thesis-2004-046.pdf
    • http://newbeams.in2p3.fr/talks/gilardoni.ppt
  • A. Cazes: Horn for SPL
    • http://tel.ccsd.cnrs.fr/tel-00008775/en/
    • http://slap.web.cern.ch/slap/NuFact/NuFact/nf142.pdf
    • http://slap.web.cern.ch/slap/NuFact/NuFact/nf-138.pdf

M. Dracos, NuFact08

main technical challenges
Main Technical Challenges
  • Horn : as thin as possible (3 mm) to minimize energy deposition,
  • Longevity in a high power beam (currently estimated to be 6 weeks!),
  • 50 Hz (vs a few Hz up to now),
  • Large electromagnetic wave, thermo-mechanical stress, vibrations, fatigue, radiation damage,
  • Currents: 300 kA (horn) and 600 kA (reflector)
    • design of a high current pulsed power supply (300 kA/100 μs/50 Hz),
  • cooling system in order to maintain the integrity of the horn despite of the heat amount generated by the energy deposition of the secondary particles provided by the impact of the primary proton beam onto the target,
  • definition of the radiation tolerance,
  • integration of the target.

M. Dracos, NuFact08

cern horn prototype
CERN horn prototype

cooling system

Current of 300 kA

p

Protons

To decay channel

B = 0

Hg Target

B1/R

initial design satisfying both, neutrino factory and super-beam

M. Dracos, NuFact08

energy deposition in the conductors

48.2 kW

67kW

14.9kW

78.7kW

Energy deposition in the conductors
  • MARS

+8kW from Joule effect

4MW, 2.2GeV proton beam

(1MeV = 1.82 kW)

M. Dracos, NuFact08

localization of the energy deposition
Localization of the energy deposition

P (kW)

target

z (cm)

z position of the particles coming out of the target

z (cm)

power deposited in the inner conductor as a function of z

M. Dracos, NuFact08

horn prototype
Horn prototype
  • For the horn skin AA 6082-T6 / (AlMgSi1) is an acceptable compromise between the 4 main characteristics:
    • Mechanical properties
    • Welding abilities
    • Electrical properties
    • Resistance to corrosion
    • Same for CNGS

…but Al not compatible with Mercury!

  • tests done with: 30 kA and 1 Hz, pulse 100 ms long
  • new tests to be done with 50 Hz

Electrical and water connections

M. Dracos, NuFact08

power supply for horn pulsing major issue
Power Supply for horn pulsing (major issue)

values considered by CERN

M. Dracos, NuFact08

3 solutions proposed by abb
3 Solutions proposed by ABB

schematic versions

at the capacitors ends

option 1

at the capacitors ends

option 2

in the charge

option 3

s

M. Dracos, NuFact08

pulser simulation parameters
Pulser simulation parameters
  • magnetic field with electrical excitation (pulses 100 μs, 50 Hz)
  • induced current distributions
  • magnetic forces
  • temperature and expansion distributions
  • mechanical constraints and deformations (static+ dynamical), vibration modes
  • non-linear magnetic and thermal effects in the calculation of mechanical constraints
  • fatigue (and constraints from radiations if any)

studies are needed to make the right choice, increase the system lifetime, reduce the cost

M. Dracos, NuFact08

new ideas

protons

protons

protons

protons

minimize power dissipation and radiation problems

(pulser problems remain as before)

2.5 m

use the advantage of the small horn size

New ideas

2.5 m

same decay tunnel Ø 3 m

to be studied in EURO

  • 2 options:
  • send at the same time 1 MW per target/horn system
  • send 4 MW/system every 50/4 Hz

possibility to use solid target?

M. Dracos, NuFact08

new crazy ideas

superconducting wire (1 mm Ø) in superfluid He,

DC power supply

New (crazy) ideas

use a cryogenic horn (toroidal coil)

blow gas He to avoid quenching problems

  • No problem with power supply (pulser no more needed)
  • Proton compressor no more needed

to be studied in EURO

M. Dracos, NuFact08

conclusions
Conclusions
  • Proton driver characteristics and target have to be fixed before horn design.
  • Preliminary studies about horn focusing performance for SPL already exist.
  • Collector studies are necessary to increase the system lifetime.
  • Target/horn integration to be considered since the beginning.
  • Multi-physics simulations would be very useful.
  • New studies will start soon in the framework of EURO FP7 project.

M. Dracos, NuFact08

slide31
End

M. Dracos, NuFact08

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