Radio-Purification of Neodymium Chloride Sunej Hans and Minfang Yeh Chemistry Department, Brookhaven National Laboratory, Upton, New York

Synthetic Pathway of Neodymium Loaded Liquid Scintillator

Prerequisites for Neodymium liquid scintillator Radio-purification (cost effect) of NdCl 3 Purified TMHA Purified LAB Radio-purification of PPO

SampleSample mass (g)Nd mass (g)Cost (US $)Density (g/cm3) Metall Nd 2 O $ Stanford Nd 2 O $1, Metall NdCl $1, NdCl 3 Unpurified very cheap1.811 NdCl 3 Purified Comparison of the different Commercially available Neodymium samples B. T. Cleveland and I. T. Lawson

Neodymium Purification 5/10/20155 Solvent extraction, ion exchanger or scavenge are conventional technologies to use; time-consuming and costly. Th(OH) 4 is very insoluble in aqueous (ksp= at 20 o C) solution; only ~10-50M of [Th 4+ ] at pH~4. Solubility of lanthanide hydroxide is >10 orders of magnitude higher than Th(OH) 4. Self-scavenge (lanthanide itself) method can be used to remove Th (and other isotopes) by adjusting pH and filtration This method can be incorporated into the M-LS production system; NO additional chemicals (secondary contamination) or exchange resin are added into the solution A simple, self-controllable method that saves time and cost

6 Gd(OH) 3 is the most insoluble in all lanthanide series If it works, all lanthanides (including Nd) should work -39 Th Self-scavenging method M. Yeh, J.B. Cumming, S. Hans, R.L. Hahn, “Purification of lanthanides for large neutrino detectors: Thorium removal from gadolinium chloride,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol 618, pp , 2010.

Th and Bi are removed 100% after pH 5.8 GdCl 3 selected for Th-229 spike experiment Using this tech. 1Kg of NdCl 3 was purified Pure NdCl 3 was sent to Bruce for Radioactive counting Results were very promising

138 La 176 Lu 40 K 227 Ac 214 Bi 208 Tl Sample (μg La/g Nd) (μg Lu/g Nd) (μg K/g Nd) (μBq/g Nd) (μBq/g Nd) (μBq/g Nd) Nd 2 O 3 Metall < ± ± 0.23 < ± ± 0.8 Nd 2 O 3 Stanford < 0.54 < ± ± ± ± 1.5 NdCl 3 Metall < ± ± 0.6 < ± ± 2.0 NdCl 3 unpur. 480 ± ± ± ± ± ± 9 NdCl 3 purified < ± ± 3 < ± ± 1.5 Tolerable ∼ × 10 −5 Recent γ activity measurements of several high-purity Nd samples with the SNOLAB Ge detector B. T. Cleveland and I. T. Lawson SNOLAB Sunej Hans and Minfang Yeh Brookhaven National Laboratory Neodymium samples Analysis with SNOLAB Ge detector

Characterization using XRF Qantitative analysis of the impure and pure lead to only 1% loss This small Loss can still save us a lots of money since the impure one is a lot more cheaper than the ultra purity one

Gamma activity measurement of purified Neodymium sample BNL purification was very successful in removing rare earth radioactive elements Purification also removed 227 Ac and 214 Bi 208 Tl activity was lowered as well by a factor of 100 BNL is capable of optimizing the purification procedure which could bring down or remove the undesired elements even to further down limits. All the activity measurements were done by B.T. Cleveland

Ahha___Bonus Point Optical transmission >300nm is greatly Improved 5/10/201511

Expanded UV (1cm) plot for Nd-LAB

Light Yield measurement Nitrogen purged sample has 16% more light yield

Conclusion Self-scavenging is proven to be working effectively Data shows the very promising results of radio-purification for NdCl 3 Th and Bi can be removed from the lanthanide (Nd) at 100% during the Nd-LS production scheme Photon production measurements were compared for sample with the nitrogenated samples. Measurements were done using gamma source Cs-137. Quality of the Neodymium sample can be further improved by optimizing the purification conditions

Acknowledgements Dr. Minfang Yeh Dr. James Cumming Dr. Liangming Hu Dr. Richard Hahn Research sponsored by the U.S. Department of Energy, Office of Nuclear Physics and Office of High Energy Physics, under contract with Brookhaven National Laboratory – Brookhaven Science Associates. Neutrino group in BNL Richard Rosero Wanda Beriguete Wai Ting Chan Dr. Jonny Goett Dr. Pankaj Sinha