Luminescence free counting of 3 H facilitated by Hidex 300 SL/600 SL TDCR triple coincidence counters. Risto Juvonen

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1 Luminesene free ounting of 3 H failitated by Hidex 300 SL/600 SL TDCR triple oinidene ounters Risto Juvonen LSC 2017 Copenhagen,

2 Hidex 300 SL and 600 SL Automati TDCR Liquid Sintillation Counters Automati vial ounters with triple- PMT detetor failitating: Exeptionally high ounting effiieny, Absolute ativity outing of beta isotopes (H-3, C-14,.. ) and Cherenkov isotopes (Y-90, Sr-89,..) using TDCR method without external radioative standard soure Luminesene free ounting mode a/b separation with 2D graphial alibration & validation tool

3 Hidex 300 SL and 600 SL Automati TDCR Liquid Sintillation Counters Automati vial ounters with triple- PMT detetor failitating: Exeptionally high ounting effiieny, Absolute ativity outing of beta isotopes (H-3, C-14,.. ) and Cherenkov isotopes (Y-90, Sr-89,..) using TDCR method without external radioative standard soure Luminesene free ounting mode a/b separation with 2D graphial alibration & validation tool

4 Luminesene interferene Luminesene is one of the main interferenes in sintillation ounting Single photon event inreasing the bakground and inreases results variation

5 Luminesene interferene Methods to redue and orreting luminesene are (1) Dark adaptation of sample (2) Chemial methods (3) Temperature ontrol (4) Counting region settings (5) Delayed oinidene ounting Many labs are ounting samples also with repeats, and removing outliers - How to find outlier? - Do I have to reount the sample or an I alulate the results using the data of remaining repeats?

6 Luminesene Free Counting method (LF method) for 3 H in water Method is based on ounting region (ROI) settings With double oinidene ounters the onventional method based on ounting regions (ROIs) works relatively well for higher energy isotopes like 14 C but yields in too low ounting effiieny for 3 H water samples. Improved LF method was tested for 3 H water samples and requires triple oinidene ounter like Hidex 300 SL or 600 SL.

7 7 Triple detetor array and oinidenes R S T: Triple Coinidene Counts S R Sample T R S: Double Coinidene Counts R T: Double Coinidene Counts S T: Double Coinidene Counts R S T R S R T S T C t = triple ounts C d = double ounts

8 Luminesene do not interfere with triple ounts 14 C in 3ml 2M NaOH + 17 ml OptiPhase HiSafe 3 3 H bkg spetra, 8 ml H 2 O + 12 ml UG ullt All ounts (blue), with luminesene peak Triple oiniodene ounts (red), no luminesene interferene In Luminesene Free mode (LF mode) only Luminesene Free Counts are reorded: 1) All Triple Coinidene ounts 2) Pure Double Coinidene ounts at above luminesene ROI (> h 120) Improved eff. Allows also 3 H water measurements in LF mode

9 Performane omparison of Lum Free mode and Normal ount mode for 3 H in water Hidex 300 SL , ml sample, 10 x 50 min, ka = kb = Normal Mode LF Mode Bkg 4.7 CPM 2.8 CPM Eff. 37 % 24 % Ld 2.6 Bq/L 1.2 DPM 3.1 Bq/L 1.5 DPM Outliers High risk Negligible risk

10 IAEA TRIC H Refene samples in LF mode Hidex SL300 test for low-level tritium. I AEA TRIC2012 referene samples were measured, pre-distilled by ion-exhange, 500 ml eletrolyti enrihments, deuterium and spike method were ompared to determine 3H enrihment fators, full error propagation applied, data was proessed using IAEA TRIMS software.

11 IAEA TRIC H Refene samples in LF mode Sample Hidex 300 SL, LF mode TRIC Ref. labs TRIC Top lab 8 ml + 12 ml UGuLLT, 20 x 50 min 2000 min Deuterium Spike TU ( 2 H) Un. TU (spike) Un. TU (known) Un. TU (known) Un. TRIC ,10 0,02 0,01 TRIC-21 0,26 0,16 0,28 0,17 0,43 0,10 0,44 0,02 TRIC-22 1,13 0,18 1,17 0,18 1,12 0,10 1,12 0,15 TRIC-23 2,71 0,20 2,81 0,20 2,74 0,07 2,70 0,04 TRIC-24 4,25 0,11 4,45 0,21 4,37 0,13 4,45 0,06 TRIC-25 7,57 0,29 7,61 0,25 7,51 0,23 7,45 0,09 *Data provided by IAEA Hydrogeology lab, Vienna Hidex 300 SL an be used to produe aurate data on LF mode for low level 3 H water samples.

12 12 Quenh Corretion in LF mode TDCR annot be used diretly in LF mode as luminesene interferes with double oinidene ounts ( d ) TDCR = d t + t = t all Availabel methods: 1. Constant quenh orretion fator (preferred when quenhing is onstant) 2. External std urve method 3. Coretion of TDCR with Chemi CPM TDCR = d t Chemi + t = t Chemi all 4. Triple Coinidene Channel Ratio method - Ratio of Triple Coinidenes in two different region used as quenh parameter => (troi1/troi2) vs. Eff. HIdex Oy / Risto Juvonen

13 13 Summary Luminesene do not interfere with triple oinidene ounts LF mode = all triples + pure doubles above luminesene ROI Improved eff. allows also 3 H water measurements in LF mode In LF mode the Eff. and Bkg are redued, Ld only slightly higher Total ounting time is redued as in LF mode ounting an be started more or less immediately after sample preparation Negligible risk for outliers In LF mode the preferred quenh orretion method is the use of Constant Quenh Corretion Fator (other methods are appliable) Hidex 300 SL and 600 SL provide aurate data in LF mode for low level 3 H water samples HIdex Oy / Risto Juvonen

14 Thank You! Risto Juvonen Produt manager Lemminkäisenkatu 62 FI Turku Tel