DAE ALUS

DAEALUS

DAEALUS

Jose Alonso, Luciano CalabrettaMIT INFN-LNS

For the DAEALUS Collaboration

High Current H2+ Cyclotrons for Neutrino Physics:

The IsoDAR and DAEALUS Projects

DAEALUSTRIUMF, Sept 13, 2012 2

Outline• Neutrino oscillations and CP violation are very hot topics!

– Background– Decay-at-rest (DAR) program

• The DAEALUS experiment– Requirements

• The IsoDAR experiment– Requirements– Siting options

• Cyclotron designs and calculations– Luciano Calabretta

• Status and Developments


Background…

• Neutrino representations in 2 sets of eigenstates:– Flavor (ne, nm, nt) related to production reaction– Mass (n1, n2, n3)

• Coupling between determined by “mixing angles”• Example (2-state system):

Flavor states


Background…

• 3-state system coupling is a “simple” extrapolation

Mass eigenstates

Flavoreigenstates


Background…

• Uij are sin/cos function of mixing angles– All now measured– q13 latest to be measured

• Some elements also contain CP violation terms ei


OscillationsPosc = sin22q sin2(1.27Dm2L/E)

P = oscillation probability sin22q = mixing strength

Dm2 = mass difference (squared) for mass eigenstates (eV2)

L = baseline length (km)E = neutrino energy (GeV)

Start with a pure ne beam

(for 2-state system)


OscillationsPosc = sin22q sin2(1.27Dm2L/E)

P = oscillation probability sin22q = mixing strength

Dm2 = mass difference (squared) for mass eigenstates (eV2)

L = baseline length (km)E = neutrino energy (GeV)

(for 2-state system)

For Dm2 ~ 2.4 x 10-3, eV2

E ~ 1 GeV,

DL ~ 1000 km (optimized Long Baseline conditions)


Oscillations (for 3-state system)



terms depending onmass splittings

terms depending onmixing angles

CP violatingterms

Sign difference between n and n



terms depending onmass splittings

terms depending onmixing angles

CP violatingterms

Sign difference between n and n


CP ViolationOption 1: Long-baseline configuration

(~1000 km, ~1 GeV neutrinos)Changing between nm and nm (- or +)

Option 2: Decay-at-rest configuration(1-20 km, ~30 MeV neutrinos)Changing baseline length (changing D)

------NOTE: HUGE benefit from combining both measurements in same detector!


Decay-At-Rest


DAR Detection• Look for appearance of ne

• Inverse beta decay (IBD) in detector with lots of free protons – Water Cherenkov or Liquid Scintillator

• Unique signature: Delayed coincidence– Huge benefit in discrimination against background

~ 2 ms




Six MW Target Concept

Copper

Graphite(hollow)

Chris Tschalaer, MIT 2011

r0 = 20 cmz0 = 8 mweight = 55 tons


Accelerator Requirements• Beam on target: ~800 MeV protons• Beam power*:

– 1.5 km site: 0.8 MW average– 8 km site: 1.6 MW average– 20 km site: 4.8 MW average

• Accelerator duty factor ~ 20%– Instantaneous power requirement is x5 average pwr___________

*Based on matching data rates in proposed 200 kTon Water Cherenkov counter, and LBNE beamline from FNAL to Homestake


Accelerator requirementsin perspective

AVERAGE power PEAK power


Cyclotrons: Viable technology?

• PSI is current world power leader in this energy range ~ 1 MW average, 590 MeV protons

• Extrapolation to higher power?_________• Problems:

1. Capture of more ions… space-charge at injection2. Clean extraction… max loss 200 W (~10-4)


Proposed Solution: H2+ ions

• Two protons for every ion (1 emA = 2 pmA)• Perveance of 5 emA H2

+ at 35 keV/amusame as 2 emA of 30 keV protons– Axial injection of 2 emA protons at 30 keV is

well within state of the art• Extract with stripping foil

– Clean turn separation is not needed, only high-acceptance extraction channel


Concept (Luciano Calabretta)INFN-Catania


Development Strategy

• With highly-complex projects:– Develop phased approach– Design phases such that good physics can be done

with each


Development Strategy

• With highly-complex projects:– Develop phased approach– Design phases such that good physics can be done

with each• In our case… Injector cyclotron can in itself

be a “barn-burning” neutrino source– The IsoDAR Project– 10 pmA (CW) at 60 MeV/amu = 600 kW!


IsoDAR (Isotope Decay At Rest)• Proton beam into neutron-producing target• Secondary neutrons into ~50 kg pure 7Li blanket• 8Li decay produces ne, high beta endpoint energy

– Good for discriminating background • As with DAEALUS, use IBD in liquid scintillator

– Good spatial, energy resolution

GOAL: STERILE NEUTRINO SEARCH


Sterile Neutrino

• Anomalies in n, n behaviors• LSND, MiniBooNE• Reactor flux anomaly

• Possible explanation:• New neutrinos that do not

interact via weak force butstill can oscillate with otherneutrino states

• Most likely Dm2 ~ 1 eV2

• DL ~ few meters!


Oscillations can be seen within detector!


SNO+ also encouraging IsoDAR


Engineering Challenges for DIC• Deliver components through narrow passage-

ways or down shafts– 4-meter diameter coil will NOT fit!

• KamLAND drive-in access, drift height < 4 meters• Creighton mine shaft (SNO+) is ~3.8 x 1.5 m

– Pole pieces too heavy for hoist• Creighton hoist has 12 ton limit

• Power and cooling • Neutron shielding

DAEALUS

DAEALUS

Luciano CalabrettaINFN-LNS

For the DAEALUS Collaboration

Cyclotron Design and Simulation Studies

DAEALUS30

Extraction trajectory

Coil

Electrostatic deflectors

TRIUMF, Sept 13, 2012

Injector Cyclotron

arXiv: 1207.4895

• 60 MeV/amu, 5 emA H2+

• Normal conducting coils ~ 4 meter coil diameter • Axial injection

(spiral inflector) • Electrostatic

extraction channel

DAEALUS31

Main parameters are extrapolated from

existing commercial compact cyclotron: C30

and TR-30

Injector Cyclotron ParametersEinj 35 keV/n Emax 60 MeV/nRinj 55 mm Rext 1.99 m

<B> at Rinj 0.97 T <B> at Rext 1.16 TSectors N. 4 Cavities N. 4

RF 49.2 MHz Harmonic 6th V-inj > 70 kV V-ext 240 kV

<DE/turn> 1.3 MeV DR at Rext 14 mmDR at Rinj >56 mm Turns N. < 952 Electrostatic Deflector (ED) + Magnetic ChannelsE. D. Gap 14 mm E.D. field 35 kV/cm

Courtesy of R. Doelling

Injection energy and acceleration voltage are higher vs. C30/TR-30

60 MeV/n after 100 turn vs. 150, or 12 msec vs. 8.1 msec

DAEALUS32

Beam size vs. turns number for different beam current

Particle’s distribution at last turn

[m]

1 MeV/n

61.7 MeV/n

See, Jianjun Yang presentation at ECPM 2012

DAEALUS33

Beam emittance 6.4 p mm.mrad, off center + 3mm at orbit of 1 MeV/n

DAEALUS34

0 10 20 30 40 50 600.9

0.95

1

1.05

1.1

1.15

E [MeV/amu]

n r

nr

50 52 54 56 58 60 620.9

0.95

1

1.05

1.1

1.15

E [MeV/amu]

n r

nr

DAEALUS35

See, Jianjun Yang presentation at ECPM 2012

Power lost on the septum of E.D. 120 W @ 600 kW!

DAEALUSCAARI – Aug 6, 2012

DAEALUS Superconducting Ring Cyclotron• H2+ injected in the ring cyclotron at 60MeV/n• Last closed orbit at 800MeV• Isochronous field. Average field ≈2T• Simulation done with OPERA3D:

– Design the structure– Define materials– Design coils– Define mesh– Solve through Tosca (FEM)– Elaborate and visualize results with Post-Processor – Optimization process

• To accelerate H2+ the magnetic field is 2 times higher than

for protons superconducting coils• Losses have to be limited to a few hundred watts in total


Outer Yoke

Pole

hill

Inner Yoke

8 SUPERCONDUCTING sector magnets:

Outer radius ≈7m

Half height 2.8m

Sector Weight

<450tons

Pole gap= 80mm

view of1/16 of the cyclotron: median plane is above the upper hill

DAEALUS Superconducting Ring Cyclotron


DAEALUS –SRC COILS

RIKEN SRC sector

RIKEN

The longest straight arms of the coils will be conncted with a plate

passing between the upper and lower hill. This will be necessary to

cancel the expansion magnetic forces which tend to make the coil

round

On the coil surface Bmodmax≈6T


DAEALUS –SRC COILS

Current density 3400A/cm2, Area 30x24cm2 or 15x48cm2

The winding of the cable could be a blocking point for cooling reasons, Huge forces developped

The different cross section is needed to guarantee enough space in the center region for the RF Cavities installation (and maybe is

not enough!)

Front view Top view


DAEALUS –SRC OPTIMIZATION RESULTS

±0.5% between isochronous and

calculated

All dangerous resonances are crossed

quicklyWalkingshaw resonance NOT crossed at the end

of acceleration

We need 10-4


DAEALUS –SRC LAYOUTBmax on the patch on the median plan 6.05TBmin on a patch on the median plan -2.5T

1 Electrostatic Deflector + 4

Magnetic channels for the injection


DAEALUS –SRC CAVITIESTwo solutions analyzed

Double gap cavity multi sistem cavity like SC

Compact Cyc

Single gap cavity like 590MeV PSI cyc

With the courtesy of L. Piazza INFN-LNL

DAEALUS43

Vertical beam size along the acceleration in the radial range from 4 to 4.9 m, snapshot at 0° azimuth. The left figure has no charge space effects, 0 mA. The right figure is evaluated with a 5 mA beam H2+ current

Simulation made by J. Yang and A. Adelman, using OPAL code

Space charge effects have

negligible effects during acceleration in

the ring cyclotron

DAEALUS

Histogram of 5 mA H2+ beam at the stripper foil position, simulation include space charge effects (OPAL code)

44

The radial size of the beam depend mainly by the energy gain

per turn

DE/E% phase (deg)

Z (mm) R (mm)

DAEALUS45

Effect due crossing Walkinshaw resonance


Steering /focusing Magnetic Channel

Extraction trajectories energy spread< ±0.6%

Stripper foils

2°proton beam

2° Stripper

DAEALUS47

Stripper foil: 5 MW beam @ 800 MeV Xing a stripper foil 1 mg/cm2 thick release 45 W due to nuclear interaction! The electrons removed by the strippers have a full power of 5 MW*Me/MH2=5/(2*1826)=1370 W !

Electrons are the main source of stripper damageBut, electrons can be stopped before strike the stripper

Stripper Thickness can be also thinner, because:H- =(p+e+e) p, e, e is a two steps process (p+e+e) H + e p, e, eH2+ =(p+p+e)p, p, e is a single step process, lower probability for H2+H + pThe neutral H can be removed by an additional stripper foil, 10 cm later

Stripper foil

emergingprotons

H2+ beam

electronscatcher

If B=0.4 T Re=4.5 mm

DAEALUS

[cm

]injection

yoke

extraction

DAEALUS

BEAM LOSSES

DAEALUS

3 major blocking points in the design

the variable cross-section that could cause

complications on the LHe cooling system

Huge residual radial FORCE that pushed

outward the coil

Not enough SPACE left between two contiguous

sectors to install RF cavities PSI like

DAEALUS

Alternative solutions AWe need an exact symmetry 8 only above 400MeV/amu -> the coil was divided in two zones. Fixing a point on the center of the hill where there is the last closed orbit, the tip of the coil was tilted by 4deg. Same with the contiguous coil ring, which was tilted by -4deg

Zone 2 symmetry 8

Zone 1symmetry 4

cavity

cavity

DAEALUS

Alternative solutions BThe stopping band resonance for a six sector machine is g=3

Why don’t use a 6-sector cyclotron?

No more issue for the RF cavities installation Easier study for injection system

Sector shape similar to Riken


0 100 200 300 400 500 600 700 8000

0.5

1

1.5

2

2.5

3

nr

nz

E [MeV/amu]

0 100 200 300 400 500 600 700 800-20

020406080

100

770 MeV/n

E [MeV/amu]

RF phase [degre]



Preliminary design study made by Joe Minervini Group at MIT-PSFC

DAEALUS

Proposed layout for an ADS plant driven by superconducting LINAC

S. Henderson, Thorium Energy Conference 2011

DAEALUSRochester, 03/04/2012 57

2.5 MW

2.5 MW

5 MW 5 MW

5 MW 5 MW

5 MW 5 MW

5 MW 5 MW

5 MW 5 MW 2.5 MW

2.5 MW

12.5 MW

12.5 MW

12.5 MW

12.5 MW

Layout of a production plant

5 cyclotrons drive 4 ADS

Each ADS is driven by 3 accelerators. Beam stability increases and decreases the number of beam trips

DAEALUS

6.25 MW 6.25 MW

6.25 MW 6.25 MW

6.25 MW 6.25 MW

6.25 MW 6.25 MW

12.5 MW

12.5 MW

12.5 MW

12.5 MW

Cyclotron OFF

In case of failure or beam trips in a cyclotron, it is possible to increase the beam current delivered by each cyclotron to maintain the beam power at 12.5 MW!


IsoDAR for Radioisotopes?

• Would 10 mA of 60 MeV protons be of interest to the radioisotope community?– Interesting target problems– OK with good beam splitting system?

• Could also be good source of 60 MeV (15 MeV/amu) alphas– Need good source of He++

DAEALUS

DAEALUS

Project Status and Roadmap


Project Status• Central region tests being set up at BEST

Cyclotrons (Vancouver)

Ion Source

HV Cage70 kV

Wien Filter“Cyclotron”

(Buncher)

Beam Stop


Goals and Schedule• To benchmark ion source and buncher

performance for H2+ ions

– Input validation for simulation codes• To explore space-charge effects and {x,y}

coupling of space-charge dominated beams• Components being built• Catania shipment in February• Run tests in late spring 2013.


On Other Fronts…• Near-term funds being sought for further engineering

design for IsoDAR• Longer-range funding for engineering studies of

DAEALUS SRC• Ion source development plans taking shape

– Vibrational states not an issue for IsoDAR– Loosely-bound H2

+ states will Lorentz dissociate in 6T at 800 MeV/amu• Must develop source that quenches these states

• Erice Workshops (12/2011, 11/2012) study design issues with cyclotron experts


Summary

• H2+ ions can be a key to high-power cyclotrons

for many applications• Compactness and relative cost of cyclotrons

could open doors to several important neutrino experiments

• Exciting times ahead!

Documents

DAE ALUS