PAA Selenium

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Using PAA ro measure Selenium concentrations.

According to Krouse<ref name="Krous1962"> H.R. Krause and H.G. Thode,"Thermodynamic Properties and Geochemistry of Iosotopic Compounds of Selenium",.Can. J. Chem., vol 40, pg 367</ref> , the fractional concentration of Se-82/Se-76 in plant material is observed to be less than from primordial (meteoric) concentrations by as much as 1.2%. Anaerobic bacteria are known to reduce selenates and senelites in biological systems. This may be the reason plant material has fractionation of selenium isotopes. They also observe excess concentrations of up to 0.4% in soil.


Plant material appears to detect environmental selenium.

Can one use plant material to measure the provenance of selenium?

As shown in the Figure below, the Se-82/Se-76 ratio varies from -1.2% to +0.2% for plant materials but remains relatively constant for other materials. The variations in plant material has been described as being due to differences in the bacteria residing in the plant. The question to investigate is whether or not these variations in the concentration can be used to determine the provenance of the sample.



Krouse Fig 1.png

Below is a table listing the natural abundances of Selenium

Natural abundance of selenium

Isotope Abundance
Se-74 0.86%
Se-76 9.23%
Se-77 7.60%
Se-78 23.69%
Se-80 49.80%
Se-82 8.82%

Below are possible PAA reactions that may be used to observe specific Se isotopes

Reaction Half-life Relative activity Gamma-rays, keV (BR)
Se-74(gamma,n)Se-73 7.1 h 1.5E-1 361 (100)
Se-74(gamma,n)Se-73m 39 m 3.2 402 (4)
Se-74(gamma,np)As-72 26 h 1.0E-3 834 (100)
Se-76(gamma,n)Se-75 120 d 1.3E-2 265(29)
Se-77(gamma,p)As-76 26.4 h 4.4E-2 559(44)
Se-78(gamma,p)As-77 38.8 h 8.6E-2 239(2)
Se-80(gamma,n)Se-79m 3.9 m 5.9 96(10)
Se-80(gamma,np)As-78 1.5 h 2.2E-2 614(54)
Se-80(gamma,p)As-79 8.2 m 1.3 96(9)
Se-80(gamma,[math]a[/math]p)Ge-75 83 m 2.8E-1 265(11)

Can one perform PAA measurements of Se-82 and Se-76?

Se_PAA_Reactions

Experiments

PAA Selenium/Soil Experiments


Nickel Normalization

LB PAA Nickel Investigation

Chlorine

It looks like Cl-35 is abundant as you see photon energies of 146 keV and 2127 keV (you can barely see 1176 keV) from Cl-34's decay (neutron knocked out of Cl-35).

The half life is 32 minutes.

Should check the half life from the run AccOnAlInDetASe-AinDetD_001.root using the calibration

MPA->Draw("0.18063+0.960133*evt.Chan>> SeRun_008(8000,0.5,8000.5)","evt.ADCid==3");

Irradiation of Horse Mineral Supplement

Below is the EMSL report for the horse feed sample. https://wiki.iac.isu.edu/index.php/File:EMSL_Report_Horse_Feed.pdf

Chlorine is a dominant signal

First, look at the peak around 146 keV 146 keV.png

Next I plotted the counts as a function of time to get an exponentially decaying graph. When doing an exponential fit here, the parameter "b" given by root will be the decay constant.

Chlorine.png

Root gives a half life of 32.9508 +/- 0.01 minutes


Now do the same for the 2127 keV line 2127 keV.png

Here are the counts plotted as a function of time 2127.png

Root gives a half life of 35.3962 +/- 0.2 minutes

Potassium is a potential signal

Looking at the spectrum for the fast irradiation sample, there are 2 prominent lines that could be from 38-K. The mechanism would be a single neutron knockout from a stable 39-K nucleus. The two most dominant energies of the three for 38-K are 2167 keV and 3936 keV and the half life is 7.63 minutes. Below is a fit to the energy spectrum histogram

2168 peak.png

Now check the half life


2167.png

Root gives a half life of 8.03 +/- 0.02 minutes

Next check the 3936 peak

3937 Peak.png

and check the half life

3936 keV halflife.png

Root gives a value for b = - 1.14372x10^(-3), which in turn gives a half life of 10.1 minutes

It seems very possible that 38-K could be in the sample of horse feed.

First Observation of Se lines

Using the 44 Machine at 7 kW power and 44 meV incident electron energy to produce a bremsstrahlung spectrum with a mean energy of 15 meV.


All runs lasting less than 214 seconds have time stamp that gives real time if you divide by clock frequency of 20 MHz.  The first 32 bits are used for a real time measurement.


MDA and Se mass Calculations

LB MDA/Se Mass Calculations

IAC Detector Efficiencies

LB PAA IAC Detector Efficiencies

Run List

Date Time elapsed (Seconds) Sample Document Title Start Stop Real Live Position
04-01-16 2.16x10^6 Se_B Se_B_002 15:55 09:15 235989.882 235687.660 k
04-06-16 2.592x10^6 Se_B Se_B_003 12:57 Interrupted computer crash k
04-14-16 3.283x10^6 Se_B Se_B_005 15:57 09:37 63581.784 63509.895 k
04-15-16 3.37x10^6 Sample D Sample_D_001 14:47 08:23 236172.264 236173.271 k
04-19-16 3.715x10^6 Sample B Sample_B_001 15:31 15:18 85634.862 85624.090 k
4-20-16 3.802x10^6 Sample C Sample_C_001 15:22 10:19 68253.774 68232.238 k
04-21-16 3.888x10^6 Sample A Sample_A_001 10:22 10:37 87292.409 87268.114 k
04-25-16 4.234x10^6 Sample E Sample_E_001 11:36 10:03 80822.406 80795.679 k
04-26-16 4.32x10^6 Se_B Se_B_008 10:06 10:29 87784.755 87664.070 k
05-05-16 5.098x10^6 Sample A Sample_A_002 13:31 14:30 3605.507 3602.925 c
05-05-16 5.098x10^6 Sample B Sample_B_002 14:34 15:26 3114.244 3112.620 c
05-05-16 5.098x10^6 Sample C Sample_C_002 15:28 10:57 70124.788 70044.470 c
05-06-16 5.184x10^6 Sample D Sample_D_002 10:59 15:34 16516.898 16512.570 c
05-06-16 5.184x10^6 Sample E Sample_E_004 15:37 16:18 261654.225 261344.308 c
05-09-16 5.443x10^6 Se B Se_B_012 16:20 11:08 67157.101 66660.298 c
05-10-16 5.5296x10^6 Sample A Sample_A_004 11:03 15:19 15379.475 15363.017 c
05-10-16 5.5296x10^6 Sample B Sample_B_004 15:22:04 11:43 73256.181 73220.324 c
05-16-16 6.048x10^6 Sample C Sample_C_004 16:33 08:19 56758.980 56711.121 c
05-18-16 6.2208x10^6 Sample D Sample_D_006 08:44:21 14:05 19271.829 19266.929 c
05-18-16 6.2208x10^6 Sample E Sample_E_006 14:08 08:06 151108.258 150955.915 c
05-20-16 6.3936x10^6 Se_B Se_B_014 08:08:47 08:44 261353.204 259621.655 c
05-23-16 6.6528x10^6 Sample A Sample_A_006 08:48 13:49 18103.004 18091.523 c
05-23-16 6.6528x10^6 Sample B Sample_B_006 13:52 13:24 84763.938 84696.083 c
05-24-16 6.7392x10^6 Sample C Sample_C_006 13:28:28 10:28 75571.716 75502.871 c
05-31-16 7.344x10^6 Sample B Sample_B_008 08:57:22 08:55 86282.861 86237.392 c
06-01-16 7.4304x10^6 Sample C Sample_C_008 08:58:39 13:31 102739.504 102647.471 c
06-02-16 7.5168x10^6 Sample D Sample_D_010 13:33 08:41 68915.044 68898.246 c

SeRun_01-11-16

LB March 2017 Runlist

SeRun_03-07-16

SeRun_02-13-17

LB IAC Radiator Specs

LB Rotating Sample Holder

LB April DetB DetA Calibration

Data Analysis

Pure Se Sample

Observed lines

LB_Feb2017_Se_Investigations

Estimate of Se-79 activity

Using known efficiency to extrapolate initial activity

Use ratio with Nickel foil rate

Se spiked in Soil

Detection limit of Se in Soil

References

User_talk:Brenleyt


<references/>

File:Krouse CanJournChem 40 1962 p367.pdf

Goryachev, A. M., & Zalesnyy, G. N. (n.d.). The studying of the photoneutron reactions cross sections in the region of the giant dipole resonance in zinc, germanium, selenium, and strontium isotopes. Retrieved September 16, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sSearch5?EntryID=220070

Goryachev, B. I., Ishkhanov, B. S., Kapitonov, I. M., Piskarev, I. M., Piskarev, V. G., & Piskarev, O. P. (n.d.). Giant Dipole Resonance on Ni Isotopes. Retrieved October 26, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sGetSubent?reqx=119235&subID=220597006&plus=1


Handbook on Photonuclear data for applications, cross sections, and spectra. (2000, October). Retrieved November 4, 2016, from http://www-pub.iaea.org/MTCD/Publications/PDF/te_1178_prn.pdf

MSDS

Selenium shot, amorphous, 2-6 mm, Puratronic, 99.999% Alfa Aesar product # 10603 File:AlphaAesarSelenium MDSD.pdf

Informative links

http://www.deq.idaho.gov/regional-offices-issues/pocatello/southeast-idaho-phosphate-mining/southeast-idaho-selenium-investigations/

https://inldigitallibrary.inl.gov/sti/3169894.pdf

http://giscenter.isu.edu/research/Techpg/sisp/index.htm


PAA_Research