Water Purification and Radium and Radon assay techniques (SNO) Jacques Farine Laurentian University LRT04 13 December 2004 Sudbury Time concentration factor:~

Water Purification and Radium and Radon assay techniques (SNO)

Jacques Farine

Laurentian University

LRT04 13 December 2004 Sudbury

Time concentration factor: ~ 2 x 10-6 s (talk-equiv.)/s (R+D work)

MnOx Bassam AharmimHTiO Xiongxin DaiRadon Richard Lange

Reactions in SNO

- Good measurement of e energy spectrum- Weak directional sensitivity 1-1/3cos()- e only.

- Measure total 8B flux from the sun.- Equal cross section for all types

NCxx

npd

ES -- ee x x

- Low Statistics - Mainly sensitive to e,, some sensitivity to and

- Strong directional sensitivity

CC-eppd e

SNO Run Sequence

1. Pure D2O

– Good CC sensitivity

2. Added Salt in D2O

– Enhanced NC sensitivity

3. Neutral Current Detectors– 3He proportional counters in the

D2O

Neutron Detection Method

Capture on D

CC: PRL 87, 7 (2001)NC: PRL 89, 011301 (2002)

Capture on Cl

PRL 92, 181301 (2004)

Capture on 3He

Event by event separation of CC and NC events

About to start production DAQ

n 3He p t

n 35Cl 36Cl … e (E = 8.6 MeV)

n d t … e (E = 6.3 MeV)

The Three Phases

Low Energy Backgrounds

“Photodisintegration” (pd)

+ d n + pIndistinguishable from NC !Technique: Radiochemical assay

Light isotropy 24Na “activation”

“Cherenkov Tail”Cause: Tail of resolution, or

Mis-reconstructionTechnique: U/Th calib. source

Monte Carlo

Daughters in U or Th chain •decays• decays

24Na

Must know U and Th concentration in D2O

Low Energy Background: Target levels

Target levels

gTh/g gU/g

D2O(0.4 n/T/y)

3.7 10-15 4.5 10-14

H2O 3.7 10-14 4.5 10-13

Measuring the U and Th ConcentrationI. Ex-situ (Radiochemical Assays)

• Extract parents to 208Tl, 214Bi and count progenies’ decay: 224Ra, 226Ra, 222Rn

Pros: better statistics

Cons: overlap with neutrino data (r,t)

II. In-situ (Low energy PMT data)

• Statistical separation of 208Tl and 214Bi using light isotropy

Pros/cons: opposite to ex-situ

III. Merge

Analysis Flow (Simplified) — Phase II

Data

Instrumental Bkg Cut

Energy, isotropy, neutron

calibrations

Signal Decomposition: CC, NC, ES

Residual Background

Part I. EX-situ techniques

The Radon assay techniqueNIM A 517 1-3 139-153

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Radon monitor degassers

H2O

D2O

58+-10% at 19 LPM 62+11-9% at 21 LPM

The Radon Collection and Concentration Apparatus

SNO’s Lucas Cell

Bgnd: 5 counts/dayCntg eff: 74% per alpha

To concentrator:100.5+-2.3%

Concentrator to LC:62+-3%

Count rate spectrumRn from D20



Radon systematics (in %)



Kd = [Ra] solid/[Ra] aqueous ~= 106

contradicting requirements !

The MnOx Radium assay techniqueNIM A 501 2-3 399-417

0.01

TEM of the MnOx coating on acrylic beads

Top view (width 7.7 m) Side view (w=0.8 m)

Radon and thorondetection efficiencyversus pressure

Radon and thorondetection efficiencyversus high voltage

Compared to simulation

∏ −=i j

ilj

jj il

imimLF

j

)!(

)())(exp(

)(

Time spectrum is a linear combination of contributions from supported and unsupported components (Bateman)

The combined likelihood function to maximize is the product of the functions:

Lj (i) : number of counts in interval i for isotope j

j=1,2,3,4 for 218Po, 216Po, 214Po, 212Po

∏∑≠=

−−

= −−=

i

jKK jk

ktti

jiEBiEj

Bj

eeA

ttm1

11

1 )()0(

),(λλ

λ

λε λλ

MnOx Data Analysis

MnOx Data Analysis, continued

212Po

216Po

MnOx SensitivityThorium chain (224Ra): 5 x 10-16 gTh/g

Uranium chain (226Ra): 2 x 10-16 gU/g

Sensitivity to the Actinium chain demonstrated (223Ra):



MnOx Systematics



R&D : Reduction of the ESC’s Background

Replace all joints with custom-made teflon gaskets

Surface contamination removal

Some counters used for developmentStrip 3 m by chemical attack• 85 liters of EDTA, 0.1 M, pH=10 • Disassemble the chamber, wipe with methanol and cover with PP bolts

the threads to avoid contact with EDTA• Put the chamber in the 18” OD tank• Fill the 18” OD tank with UPW (Rinse the chamber 2 times)• Fill with EDTA and let the chamber to soak in for 2h, agitate• Rinse the chamber with UPW, 3 times• Use Methanol to wash and dry the chamber • Assemble the chamber and start a BGND”C”.

R&D : Reduction of the ESC’s Background

Date Type+ Pressure mbCounting time

dCPD 214Po CPD 216Po 224Ra dpd 226Ra dpd

Reference values before actions

08/04/2004BGND"C" NF

(P=2626)19.25 13.90.8 2.50.4 9 (8-10) 60 (57-62)

After EDTA cleaning

28/08/2004BGND"C" NF(P=2439)

17.75 12.50.9 1.20.3 6 (5-7) 29 (26-33)

After Teflon conversion

17/09/2004BGND"C" NF(P=2628)

13.03 6.10.7 1.50.3 5 (4-6) 18 (15-21)

ESC#9

ESC#7

Date Type+ Pressure mbCounting time d

CPD 214Po CPD 216Po 224Ra dpd 226Ra dpd

Reference values before actions

19/05/2004BGND"C" (P=3439)

19.25 61.12.2 9.10.8 40 (36-44) 292 (283-301)

After Teflon conversion

08/10/2004BGND"C" (P=3435)

9.67 26.51.7 8.20.9 43 (40-46) 117 (109-125)

After EDTA cleaning

10/11/2004BGND"C" (P=3435)

10.88 27.21.6 10.21.0 46 (43-49) 97 (90-105)

R&D : Calibration of the ESC’s using Th spike

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0

100

200

300

400

500

Counts/3h

Time (d)

212Po 216Po 212Bi

R&D : Calibration of the ESC’s using Th spike

0 10 20 30 40 50 60 70 80 90

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

Relative efficiency vs. 26 mbar

N2 pressure (mbar)

216Po 212Po

Assay and Purification of Ultra-low Level Radioactivity using

Hydrous Titanium Oxide Adsorbent(HTiO)

Xiongxin Dai

University of Carleton

Modified HTiO procedure for 228Th, 224Ra and 226Ra in SNO water

Total chemical efficiencies: Ra: 508%; Th: 28%Total efficiencies: 307% for 226Ra; 224% for 224Ra; 12% for 228Th

- delayed coincidence liquid scintillation counter

Ra: 95%; Th: 95%

SecondaryConcentration

Elution

~ 200T D2O (or 30T H2O)

HTiO coated ultrafilters

15 L 0.1M HCl

100 ml 0.25M EDTA (pH 10) 50 ml 4M H2SO4

12.0 g of Dowex 50WX8 resin

4.0 g of Dowex 1X8 resin

Dissolve in 2 ml conc. HCl

Extraction

Counting

ThRa

Ra

Ra

Ra

Ra

Ra

Ra

Th

Th

Th

Th

Th

ThRa: 90%; Th: 65%

Ra: 58%; Th: 45%

Th chain: 455%U chain: 6010%

Co-precipitation with HTiO

Co-precipitation with HTiO

80 ml 0.5M HCl, and evaporateTh

Radium and thorium assay for leaching test

Total chemical efficiencies: Ra: 8610%; Th: 88 10

%- delayed coincidence liquid

scintillation counter

Elution

< 15 L of water sample

Add 1-2 ml of 15% Ti(SO4)2 solution

Trap HTiO precipitate onto small ultrafilter

Elute Ra and Th into 10 ml of 0.5M HCl

Titrate with NaOH to pH 9; Ra and Th co-precipitate with HTiO

Extraction

Counting Th chain: 455%U chain: 6010%

Ra: 982%Th: 955%

Ra: 9010%Th: 9010%

Total efficiencies: 5111% for 226Ra; 386% for 224Ra; 40 6 % for 228Th

Procedural blanks: 0.30.1 cph for 226Ra; <0.05 cph for 224Ra and 228Th

Measurement of 238U in water sample

Detection limit (200-tonne assay): < 10-16 g/g

ICP-MS analysis

Elution

Water sample

HTiO coated ultrafilters

Elute U into 0.03M HNO3

Extraction

Detection

955%

9010%

Purification of radioactivities using HTiO adsorbent

- Targets: Ra, Pb, U and Th isotopes

- Sample types: Water, salt and liquid scintillator etc

- Purification methods:

HTiO co-precipitation

HTiO loaded-ultrafiltration

HTiO loaded-resin

Link Assays Results to data • Multiple sources model

– Identify other sources in the systems– System’s history (flow rate, flow path, times ...)– Reconstruct time profile of activity in fiducial volume DAN

• Identify other sources: “Peristaltic assays”– D2O systems idle for long periods - all valves closed– Study Ra leach rate of isolated components– Procedure:

• drain/vents on closed subsystem - use to draw/return D2O• mount a MnOx column + use a peristaltic pump - no contact with D2O

28 2723

+−

233 5048

+−

7634

31

+

−

7142

37

+

−

39 2622

+−

72 3330

+− 15

28

26

+

−

75 3129

+−

2629

26

+

−031208_3<36030813FR-09

<27031202030731

PDG

031208_4030730P-01

<24031208_2030729_2UFR-05

031208_1

031125

030729_1HX-91

<11040129030710UFR-01

224Ra @ EOE (dpd)

Exp- ID224Ra @ EOE (dpd)

Exp- ID

After desalinationSalt PhaseSubsystem

Peristaltic Assays - Results

Prior to salt addition < 16 dpd

Salt brine assayed - no Th added

Most of the activity is gone with the salt

Cl and Na in waterchanged [Ra]bd/[Ra]aqat sources in systems

Part II. in-situ analysesLight isotropy

Phase I:• CC, NC, ES: Single e

Phase II:• CC, ES: Single e• NC: Mostly multiple e’s

multiplicity means PMT hit pattern for neutron events moreisotropic than for single Cherenkov electrons

• The rotationally invariant “Legendre Polynomial Isotropy Parameter”:

where

was chosen for its good separation of the CC and NC signal and the ease of systematic characterization

MoreIsotropic

Reconstructed event position

ith PMT

jth PMT

ij

€

l =2

N (N −1)Pl

j =i +1

N

∑i =1

N −1

∑ (cosθij )

€

1 +4β4

Calibrating the Light Isotropy Parameter

Cherenkov Tail

New technique: Rn ‘Spikes’

Merging ex- and in-situ

results

Merging ex-situand in-situ results

Good agreement

Th (224Ra) concentrationat the level of 4 atoms/ton

Levels below targets

Documents

Water Purification and Radium and Radon assay techniques (SNO) Jacques Farine Laurentian University LRT04 13 December 2004 Sudbury Time concentration factor:~