Production of high intensity beams for the beta beams: status report

T.M. Mendonça1, R. Hodak2, M. Allibert3, V. Ghetta3, D. Heuer3, E. Noah4, T. Stora1

1 CERN 2 Comenius University

3 LPSC Grenoble 4 ESS

6He and 18Ne production for the Beta Beams

6He production using BeO target at ISOLDE - Target synthesis and characterization - Online validation at ISOLDE

18Ne production using molten salts

- Molten salts synthesis and characterization (collab. LPSC/Grenoble) - Preparation of the static target unit and online tests (collab. Comenius Univ., Slovakia) - Design of a circulating molten salts loop (collab. LPSC)

RCS   SPL   Linac4  

ISOL  target   Molten  Salt  Loop  

6He   18Ne  

RFQ  

ECR  

6He/18Ne  Baseline  

Production of radioactive ion beams based on the ISOL technique

Primary beam (MeV/u-GeV/u)

Leaks   Leaks  Leaks   Neutrals  

Baseline ions: 6He (T1/2=0.8 s, Qβ-=3.5 MeV) and 18Ne (T1/2=1.67 s, Qβ- =3.3 MeV) Production of anti- νe and νe: 3(.3)x1013 6He/s and 2(.1)x1013 18Ne/s out of the primary target (Final report, FP6 EURISOL-DS)

ISOL method: higher intensities and better beam quality

U. Köster et al., EURISOL-DS

T. Stora et al., EURISOL-DS, TN03-25-2006-0003

Production of 6He using beryllium oxide target

Standard ISOLDE target and spallation source configuration

Reaction: 9Be(n,α)6He

σ→ 9Be(n,α)6He!EXFOR data!

BeO Target

(p‐n) W Converter

p (1.4 GeV)

Optimized geometry: target surrounding the converter

BeO target: production and characterization (R. Hodak)

80 porous ceramic BeO pellets

Vacuum furnace

Max. temperature 2000ºC

1.88

cm

Thickness:0.2 cm

Nominal density – 71% Stability at 1400 °C Good thermal conductivity Compatibility with rhenium Fast ageing and chemical

reaction with other metals Rhenium boat

1  µm  

Appropriate target material

0 200 400 600 800 1000 1200 14000,0005

0,0010

0,0015

0,0020

0,0025

0,0030

0,0035

0,0040

 E ffic iency  E F F  (U s er)  F it  of  E ffic iency

Efficien

cy

E nerg y  [keV ]

E quation y  =  exp(A+B*ln(x/1000.)+C *ln(x/1000.)^2+D*ln(x/1000.)^3+E *ln(x/1000.)^4)

Adj.  R -­‐S quare 0,98981Value S tandard  E rror

E fficiency A -­‐6,58123 0E fficiency B -­‐0,63011 0,05828E fficiency C -­‐0,38602 0,0613E fficiency D -­‐0,27717 0,01514E fficiency E -­‐0,06626 0

HPGe Detector

Estimation of in target 6He production Neutron spectrum characteristics

- FLUKA simulations - Activation Foils method (Al, Ni, In, Bi in 3 different positions

Cross sections of the fast neutrons induced reactions

Unfolded neutron spectra with Fluka and Geant

T. Stora, E. Noah, R. Hodak, T.Y. Hirsh, M. Hass, K. Singh, S. Vaintraub, P. Delahaye, M.G. St Laurent, G. Lhersonneau, Submitted to EPL

Release efficiency (>85% released) Release curve provides additional information on performance of target

and ion source unit Yield determination requires measurement of entire release curve

In target rates: v 1.3x1013 6He/s 100kW, 40 MeV deuteron beam v  2x1013 6He/s 100kW, 1 GeV proton beam v 1x1014 6He/s 200kW, 2 GeV proton beam

BeO validation at ISOLDE

M. Hass et al., J. Phys. G 35, 014042 (2008) T. Hirsch et al. PoS (NuFact08) 090

Yield  (6He  ions/µC)  

T. Stora, E. Noah, R. Hodak, T.Y. Hirsh, M. Hass, K. Singh, S. Vaintraub, P. Delahaye, M.G. St Laurent, G. Lhersonneau, Submitted to EPL

6He  release  curve  at  1400ºC  

18Ne production using molten fluoride salts

-  A proposal inspired from 18F production for PET imaging -  Molten salts tested and operated at ISOLDE (CERN 70-03, CERN 81-09)

-  Molten salt targets (LiF): validated at Louvain-la-Neuve using 9 kW, 30 MeV proton beam  

Prototype and future tests: -Optimized static sodium molten salt unit at CERN/ISOLDE (IS509) -Molten salt loop (in collaboration with LPSC/Grenoble)  

Molten salt targets validated at ISOLDE TeO2:K2Cl2:Li2Cl2 (molar ratio 29:25:46), Tm~347(5)ºC

 

(CERN 81-09)

TeCl3 with Tm~224ºC  

(CERN 70-03)

Molten salts in solar power industry and in optics

Mixture of NaNO3:KNO3 (60:40 % mol.) - Used in solar power tower systems (Spain, U.S.A, Australia, Italy) - Efficient and low cost medium to store thermal energy - Salt storage system lowers cost of solar plant operation

Molten alkali fluorides: - High electric conductivity - Heavy metal fluoride glass compositions for fabrication of mid-infrared, ultra low loss optical fibers  

http://www.gizmag.com/california-first-molten-salt-solar-power-plant/17298/

Gemasolar Array, Spain

T. Stora, P. Valko

2.1 L/s

NaF-ZrF4 at 700ºC

Proposal for 18Ne production: NaF target loop (23Na(p, X)18Ne, 19F(p,2nα)18Ne)

6mA 160MeV

2.1 L/s

NaF:ZrF4 at 600ºC or NaF:LiF at 700ºC

7.5x24x15cm

40x15x15cm

Transfer line to ion source

Target and container materials

Haynes 242 alloy chemical composition (%weight)

Ni Mo Cr Fe Co Mn Si Al Cu

Haynes 242 65 25 8 2 2.5 0.8 0.8 0.5 0.5

Container in fluoride resistant alloy (Haynes 242) (Machined at Cern Main Workshop, EN-MME-MS)

Salt Composition

[mol %]

Melting point

[ºC]

Density [g/cm3]

(700 ºC) Vapor pressure

[mmHg](900ºC) Yield protons 6mA 160MeV

NaF-BeF2 57 - 43 340 2.01 1.4 8.8E+012

NaF-NaBF4 8 - 92 385 1.75 9500 8.4E+012

NaF-ZrF4 60 - 40 500 3.14 5.1 1.0E+013

NaF-LiF 61-39 649 2.59 1 1.0E+013* (7 mA)

Synthesized NaF-ZrF4 salt

Synthesis of NaF-ZrF4 salts Mixture of stoichiometric quantities of NaF and ZrF4 and heating up to 600ºC under vacuum Initial mixture with 50:50% mol accounting for ZrF4 losses (ZrF4 sublimation at 600ºC)

All handling and manipulation in gloveboxes under controlled argon atmosphere

Starting reactants previously dried at 350ºC/72hrs in vacuum

Characterization of NaF-ZrF4 salts

20  µm  

SEM/EDS analyses (Collab. S. Sgobba, EN-MME-MM)

0 5 10 15 20Energy (keV)

0

10

20

30

40

50cps

F

Na

Zr

Zr

Zr

Zr ZrZr

Elmt   Atomic  %   mol    

F    77.34513   2.23  Na    13.43286   0.59  Zr    9.22199   0.41  

Characterization of NaF-ZrF4 salts Differential scanning calorimetry (DSC) (collab. M.Taborelli ,TE-VSC-SCC)

Temperature     Phases  below  T   Phases  above  T  

500C  (start  of  fusion)  

 3NaF:2ZrF4  (solid)   γ2NaF:ZrF4,    7NaF:6ZrF4  (ss)  

506C    γ2NaF:ZrF4,  7NaF:6ZrF4  (ss)   γ2NaF:ZrF4  (liquid)  

525C    γ2NaF:ZrF4,  Liquid  phase  

Liquid  phase  

Preparation of the target unit

Salt reduced to powder

88% of nominal density (3.15 g/cm3 at RT, 2.54 g/cm3 at 800C), Quantity calculated according to volume occupied at 800C

194 mm

Preparation of the target unit: offline tests - Temperature calibration showed a melting point at c.a. 600(10)ºC accompanied by an exothermic reaction – in disagreement with nominal melting point and DSC measurements - Possible causes: loss of ZrF4 and consequent higher melting point; density of the powder lower than the estimated; high ZrF4 vapor pressure

194 mm

Ttarget   Tchimney  

Offline tests (continuation)

ZrF4(g)+2H2O(g) ZrO2(s)+4HF(g)

Reaction observed at 600ºC phase separation of NaF-ZrF4 salt

Salt oxidation and decomposition

Use of graphite as container: Less wettability

Mass losses vs. T

0.8  m  

0.4  m  

0.6  m  

1.8  m  

Furnace  

Diffusion  chamber  Camera  (or  

window  in  the  chamber)  

Molten salt loop: Pb/Bi loop developed at IPUL Experimental program at IPUL/Latvia showed feasibility of a molten Pb/Bi

shower to accomodate 100 kW, 1GeV incoming proton beam

Na molten salt loop: some ideas on the diffusion chamber

Liquid-metal loop setup at IPUL: final Report EURISOL DS, 2009 (E. Noah et al.)

To confirm experimentally: - Thermal stability of NaF:ZrF4 (ZrF4 sublimates at temperatures relevant for operating conditions) - Alternative composition NaF:LiF (estimated yield: 1013 18Ne/s for 7 mA, 160 MeV) – better thermal behavior expected

ZrF4

NaF

LiF

Lower vapour pressures for NaF and LiF

Eutectic with melting point at ~649ºC

NaF:LiF molten salt: alternative target material?

- Online validation of the chosen target material using a static unit at ISOLDE (2012) using optimal target compositions and running conditions (tests ongoing) - Loop design

Future Plans To confirm experimentally: - Thermal stability of NaF:ZrF4 (does ZrF4 sublimate at temperatures relevant for operating conditions?) - Alternative composition NaF:LiF (estimated yield: 1013 18Ne/s for 7 mA, 160 MeV) – better thermal behavior expected