Production of high intensity beams for the beta beams: status report T.M. Mendonça 1 , R. Hodak 2 , M. Allibert 3 , V. Ghetta 3 , D. Heuer 3 , E. Noah 4 , T. Stora 1 1 CERN 2 Comenius University 3 LPSC Grenoble 4 ESS
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