Difference between revisions of "PAA Selenium"

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=Can one use plant material to measure the provenance of selenium?=
 
=Can one use plant material to measure the provenance of selenium?=
  
−
=Can one perform PAA measurements of Se-82 and Se-76?=
+
[[Se_Overview_PrevMeas]]
−
 
 
−
 
 
−
==Neutron knockout of Se-82==
 
−
If you knock a neutron out of Se-82 you produce the unstable isotope Se-81 which Beta emitts with half life of 18 min and a meta-state that emmits a 103 keV gamma with a 57 minute half life.
 
−
 
 
−
<math>{82 \atop 34\; }Se (\gamma,n){81 \atop \; }Se</math>
 
−
 
 
−
Other prominent photons
 
−
 
 
−
260 & 276 keV for the 57 minute half life isotope
 
−
 
 
−
==Neutron knockout of Se-76==
 
−
If you knock a neutron out of Se-76 you produce the unstable isotope Se-75 which has a half life of 119 days.
 
  
−
<math>{76 \atop\; }Se (\gamma,n){75 \atop \; }Se</math>
+
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.
  
−
The prominent photons emitted have the following energies
 
  
−
136, 264, and 279 keV
 
  
  
−
The article below describes how plant material and soil contain Se-76 to Se-82 ratios that differ from other natural samples by 1.5%.  They argue that it is due to the bacteria living in plant material. 
+
[[File:Krouse_Fig_1.png | 200 px]]
−
 
 
−
[[File:Krouse_CanJournChem_40_1962_p367.pdf]]
 
−
 
 
−
Plant material is a natural way to sample the selenium content to determine if there are difference isotopic ratios due to the impact of human activities on the environment.
 
−
 
 
−
=Experiments=
 
−
 
 
−
==Chlorine==
 
−
 
 
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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==
 
−
 
 
−
=== Chlorine is a dominant signal===
 
−
 
 
−
 
 
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First, look at the peak around 146 keV
 
−
[[File:146_keV.png | 200 px]]
 
−
 
 
−
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.
 
−
 
 
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[[File:146_keV_halflife.png | 200 px]]
 
−
 
 
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Root gives a value b = 3.59543x10^-4, which yields a half life of 32.1 minutes.
 
−
 
 
−
 
 
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Now do the same for the 2127 keV line
 
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[[File:2127_keV.png | 200 px]]
 
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Here are the counts plotted as a function of time
 
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[[File:2127_keV_halflife.png | 200 px ]]
 
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Root gives b = 3.26947x10^-4, which yields a half life of 35.3 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
 
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[[File:2168_peak.png | 200 px]]
 
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Now check the half life
 
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−
 
 
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[[File:2167_keV_halflife.png | 200 px]]
 
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Root gives a value for b = -1.44218x10^(-3), which in turn gives a half life of 8 minutes
 
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−
Next check the 3936 peak
 
−
 
 
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[[File: 3937_Peak.png | 200 px ]]
 
−
 
 
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and check the half life
 
−
 
 
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[[File: 3936_keV_halflife.png | 200 px ]]
 
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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.
 
−
 
 
−
== Detector Efficiency ==
 
−
 
 
−
Below is the runlist for finding the efficiency of the detector at position R
 
  
 +
== Below is a table listing the natural abundances of Selenium==
 +
Natural abundance of selenium
  
 
  {| border="3"  cellpadding="5" cellspacing="0"
 
  {| border="3"  cellpadding="5" cellspacing="0"
−
|  Source || Serial # || Reference Date || Activity || Start || Stop || Live 
+
|  Isotope|| Abundance
 +
|-
 +
| Se-74  || 0.86%
 
|-
 
|-
−
| Na-22  || 129743 || 7-01-08 || 9.427 microCi || 15:49 || 16:19 || 1796.803 
+
| Se-76 || 9.23%
 
|-
 
|-
−
| Cs-137 || 129793 || 7-01-08 || 1.006 microCi || 14:25 || 14:56 || 1879.606
+
| Se-77 || 7.60%
 
|-
 
|-
−
| Mn-54 || 129807 || 7-01-08 || 11.77 microCi || 15:00 || 15:30 || 1793.420
+
| Se-78 || 23.69%
 
|-
 
|-
−
| Co-60 || 129740 || 7-01-08 || 10.42 microCi || 15:33 || 15:43 || 569.725
+
| Se-80 || 49.80%
 
|-
 
|-
 +
| Se-82 || 8.82%
 
|}
 
|}
  
−
Below are the theoretical calculations for the theoretical decay frequencies
+
== Below are possible PAA reactions that may be used to observe specific Se isotopes==
−
 
 
−
Na-22, 9.427micro Ci on July 1, 2008, half life 2.602 +/- 0.002 years, 99.937% for 1274.52 and 178.8 for 511 line , activity in March 31, 2016 =1.196micro Ci
 
−
:= <math>\left (0.99937 \right )\left ( 1.196 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 44,224 Hz </math> for the 1274 line
 
−
 
 
−
:= <math>\left (1.788 \right )\left ( 1.196 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  79122.6 Hz </math> for the 511 line
 
−
 
 
−
Cs-137, 661.660 line, 85.21% * 1.066micro Ci on July 1, 2008, half life 30.0 +/- 0.2 yrs, March 31, 2016 activity = 0.891micro Ci expected rate for 661 line
 
−
 
 
−
:= <math>\left (0.8521 \right )\left ( 0.891 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 28091.2 Hz </math>
 
−
 
 
−
Mn-54, 11.77 microCi  on July 1, 2008, half life =312.20 +/- 0.07 days, 99.975% intensity on 834.826 , March 31, 2016 activity =0.02328micro Ci
 
−
 
 
−
:= <math>\left (0.99975 \right )\left ( 0.02328 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  861.1 Hz </math> for the 834 line
 
−
 
 
−
 
 
−
Co-60, 10.42micro Ci July 1, 2008, half life 5.271 +/- 0.001 years, 99.0 % for 1173.237 and 99.9824 % for 1332.501, March 31, 2016 activity=3.759micro Ci
 
−
 
 
−
 
 
−
:= <math>\left (0.99 \right )\left ( 3.759 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 137692.17 Hz </math> for the 1173 line
 
−
 
 
−
 
 
−
:= <math>\left (0.999824 \right )\left ( 3.759 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  139058.52 Hz </math> for the 1332 line
 
−
 
 
−
 
 
−
Below is a table where the actual efficiency will be calculated for position R (farthest position).
 
  
 
  {| border="3"  cellpadding="5" cellspacing="0"
 
  {| border="3"  cellpadding="5" cellspacing="0"
−
|  Run || Source || Energy (keV) || Expected Rate (Hz) || HpGe Rate (Hz) || HpGe Det D Efficiency (%)  
+
|  Reaction|| Half-life ||Relative activity ||Gamma-rays, keV (BR)
 
|-
 
|-
−
| Eff_003 || Na-22 || 511 || 79122.6 || (506:516) (4.309-0.065=4.244) || 0.005
+
| Se-74(gamma,n)Se-73 || 7.1 h || 1.5E-1 || 361 (100)
 
|-
 
|-
−
| Eff_005 || Cs-137 || 661.657 || 28091.2 ||(657:666)(1.105-0.02281=1.0821) ||0.004
+
| Se-74(gamma,n)Se-73m  || 39 m || 3.2 || 402 (4)
 
|-
 
|-
−
| Eff_006 || Mn-54 || 834.848  || 861.1 ||(830:839)(0.04037-0.009123=0.031247)||0.004
+
| Se-74(gamma,np)As-72 || 26 h || 1.0E-3 || 834 (100)
−
|-
 
−
| Eff_007 || Co-60 || 1173.228 || 137692 ||(1164:1182)(3.686-0.01939=3.67)||0.003
 
 
|-
 
|-
−
| Eff_003 || Na-22 || 1274.537 || 44224 ||(1270:1279) (1.073-0.0057=1.0673)||0.002
+
| Se-76(gamma,n)Se-75  || 120 d || 1.3E-2 || 265(29)
 
|-
 
|-
−
| Eff_007 || Co-60 || 1332.492 || 139058.52 ||(1328:1337)(3.283-0.05702=3.22598)|| 0.002
+
| 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)
−
Below is a runlist for position k
 
−
 
 
−
{| border="3" cellpadding="5" cellspacing="0"
 
−
| Source || Serial # || Reference Date || Activity || Start || Stop || Live 
 
 
|-
 
|-
−
| Na-22 || 129743 || 7-01-08 || 9.427 microCi || 14:54 || 15:01 || 434.087 
+
| Se-80(gamma,n)Se-79m || 3.9 m || 5.9 || 96(10)
 
|-
 
|-
−
| Cs-137 || 129793 || 7-01-08 || 1.006 microCi || 15:48 || 15:55 || 413.925
+
| Se-80(gamma,np)As-78 || 1.5 h || 2.2E-2 || 614(54)
 
|-
 
|-
−
| Mn-54 || 129807 || 7-01-08 || 11.77 microCi || 15:28 || 15:40 || 705.186
+
| Se-80(gamma,p)As-79  || 8.2 m || 1.3 || 96(9)
 
|-
 
|-
−
| Co-60 || 129740 || 7-01-08 || 10.42 microCi || 15:41 || 15:47 || 346.092
+
| Se-80(gamma,<math>a</math>p)Ge-75  || 83 m || 2.8E-1 || 265(11)
 
|-
 
|-
 
|}
 
|}
  
−
Below are the theoretical decay frequencies
+
=Can one perform PAA measurements of Se-82 and Se-76?=
  
−
Na-22, 9.427micro Ci on July 1, 2008, half life 2.602 +/- 0.002 years, 99.937% for 1274.52 and 178.8 for 511 line , activity in April 14, 2016 =1.183micro Ci
+
[[Se_PAA_Reactions]]
−
:= <math>\left (0.99937 \right )\left ( 1.183 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 43743.4 Hz </math> for the 1274 line
 
  
−
:= <math>\left (1.788 \right )\left ( 1.183 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 78262.5  Hz </math> for the 511 line
+
=Experiments=
  
−
Cs-137, 661.660 line, 85.21% * 1.066micro Ci on July 1, 2008, half life 30.0 +/- 0.2 yrs, April 14, 2016 activity =0.890 micro Ci expected rate for 661 line
+
==[[PAA_Selenium_ActivityCalc]]==
  
−
:= <math>\left (0.8521 \right )\left ( 0.890 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 28059.7 Hz </math>
+
[[PAA Selenium/Soil Experiments]]
  
−
Mn-54, 11.77 on July 1, 2008, half life =312.20 +/- 0.07 days, 99.975% intensity on 834.826 , April 14, 2016 activity =0.02251micro Ci
+
[[LB Se PAA Horse Feed Experiment]]
  
−
:= <math>\left (0.99975 \right )\left ( 0.02251 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 830.79 Hz </math> for the 834 line
+
==Background Signals==
 +
[[PAA_BackGrd_Det_A]]
  
 +
==Nickel Normalization==
 +
[[LB PAA Nickel Investigation]]
  
−
Co-60, 10.42micro Ci July 1, 2008, half life 5.271 +/- 0.001 years, 99.0 % for 1173.237 and 99.9824 % for 1332.501, April 14, 2016 activity=3.74micro Ci
+
== 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.
  
−
:= <math>\left (0.99 \right )\left ( 3.74 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  136996.2 Hz </math> for the 1173 line
 
  
 +
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.
  
−
:= <math>\left (0.999824 \right )\left ( 3.74 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  138355.6 Hz </math> for the 1332 line
 
  
−
Below are the actual efficiencies for position k
+
== MDA and Se mass Calculations ==
 +
[[LB MDA/Se Mass Calculations]]
  
−
{| border="3"  cellpadding="5" cellspacing="0"
+
==IAC Detector Efficiencies ==
−
|  Run || Source || Energy (keV) || Expected Rate (Hz) || HpGe Rate (Hz) || HpGe Det D Efficiency (%) 
 
−
|-
 
−
| Eff_k_002  || Na-22 || 511 || 79122.6 || (506:516)(49.21-0.6272=48.58) || 0.06
 
−
|-
 
−
| Eff_k_006 || Cs-137 || 661.657 || 28091.2 ||(657:666)(12.86-0.02281=12.837) ||0.05
 
−
|-
 
−
| Eff_k_004 || Mn-54 || 834.848  || 861.1 ||(830:839)(0.3204-0.009123=0.311)||0.04
 
−
|-
 
−
| Eff_k_005 || Co-60 ||  1173.228 || 137692 ||(1164:1182)(42.39-0.02053=42.369)||0.03
 
−
|-
 
−
| Eff_k_002 || Na-22 || 1274.537 || 44224 ||(1270:1279) (12.53-0.005702)=12.52||0.03
 
−
|-
 
−
| Eff_k_005 || Co-60 ||  1332.492 || 139058.52 ||(1328:1337)(35.94-0.005072)|| 0.03
 
−
|}
 
  
−
Below is a runlist for position C
+
[[LB PAA IAC Detector Efficiencies]]
  
−
{| border="3"  cellpadding="5" cellspacing="0"
+
==IAC Detector Calibrations==
−
|  Source || Serial # || Reference Date || Activity || Start || Stop || Live 
 
−
|-
 
−
| Na-22  || 129742 || 7-01-08 || 1.146 microCi || 12:55 || 12:57 || 129.782 
 
−
|-
 
−
| Cs-137 || 129793 || 7-01-08 || 1.006 microCi || 13:02 || 13:04 || 123.818
 
−
|-
 
−
| Mn-54 || 129806 || 7-01-08 || 1.226 microCi || 13:11 || 13:21 || 613.754
 
−
|-
 
−
| Co-60 || 129739 || 7-01-08 || 1.082 microCi || 13:08 || 13:09 || 103.599
 
−
|-
 
−
|}
 
  
−
Below are the calculations for the theoretical frequencies
+
[[LB April DetB DetA Calibration]]
  
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Na-22, 9.427micro Ci on July 1, 2008, half life 2.602 +/- 0.002 years, 99.937% for 1274.52 and 178.8 for 511 line , activity in May 5, 2016 =1.196micro Ci
+
==Runlists==
−
:= <math>\left (0.99937 \right )\left ( 0.14 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 5176.7 Hz </math> for the 1274 line
+
[[LB PAA Runlist 4/01/16 - 06/02/16]]
  
−
:= <math>\left (1.788 \right )\left ( 0.14 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  9261.8 Hz </math> for the 511 line
+
[[LB March 2017 Runlist]]
  
−
Cs-137, 661.660 line, 85.21% * 1.066micro Ci on July 1, 2008, half life 30.0 +/- 0.2 yrs, May 5, 2016 activity = 0.89micro Ci expected rate for 661 line
+
[[LB_May_2017_Irradiation_Day]]
  
−
:= <math>\left (0.8521 \right )\left ( 0.891 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 28059.7 Hz </math>
+
=Data Analysis=
  
−
Mn-54, 1.226 microCi on July 1, 2008, half life =312.20 +/- 0.07 days, 99.975% intensity on 834.826 , May 5, 2016 activity =0.002micro Ci
 
  
−
:= <math>\left (0.99975 \right )\left ( 0.002 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  73.98 Hz </math> for the 834 line
+
[[LB_Feb2017_Se_Investigations]]
  
 +
=References=
  
−
Co-60, 1.082micro Ci July 1, 2008, half life 5.271 +/- 0.001 years, 99.0 % for 1173.237 and 99.9824 % for 1332.501, May 5, 2016 activity=0.39micro Ci
 
  
 +
[[User_talk:Brenleyt]]
  
−
:= <math>\left (0.99 \right )\left ( 0.39 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  14285.7 Hz </math> for the 1173 line
 
  
 +
<references/>
  
−
:= <math>\left (0.999824 \right )\left ( 0.39 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)=  14427.5 Hz </math> for the 1332 line
+
[[File:Krouse_CanJournChem_40_1962_p367.pdf]]
−
 
 
−
Below is a table with the calculated efficiencies
 
−
 
 
−
{| border="3"  cellpadding="5" cellspacing="0"
 
−
|  Run || Source || Energy (keV) || Expected Rate (Hz) || HpGe Rate (Hz) || HpGe Det D Efficiency (%) 
 
−
|-
 
−
| Eff_C_001  || Na-22 || 511 || 9261.8 || (506:516) (45.65-0.065=45.585) || 0.5
 
−
|-
 
−
| Eff_C_002 || Cs-137 || 661.657 || 28059.7 ||(657:666)(101.7-0.02281=101.67) || 0.4
 
−
|-
 
−
| Eff_C_004 || Mn-54 || 834.848  || 73.98 ||(830:839)(0.2704-0.009123=0.2612)||0.4
 
−
|-
 
−
| Eff_C_003 || Co-60 ||  1173 || 14285.7 ||(1164:1182)(34.24-0.01939=34.22)||0.2
 
−
|-
 
−
| Eff_C_001 || Na-22 || 1274.537 || 5176.7 ||(1270:1279) (11.15-0.0057=11.14)||0.2
 
−
|-
 
−
| Eff_C_003 || Co-60 ||  1332.492 || 14427.5 ||(1328:1337)(28.05-0.05702=27.99)|| 0.2
 
−
|}
 
−
 
 
−
=Run List=
 
  
−
{| border="3"  cellpadding="5" cellspacing="0"
+
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
−
|  Date || Time elapsed (Seconds) || Sample || Document Title || Start || Stop || Real || Live 
 
−
|-
 
−
| 04-01-16  || 2.16x10^6 || Se_B || Se_B_002 || 15:55 || 09:15 || 235989.882 || 235687.660
 
−
|-
 
−
| 04-06-16 || 2.592x10^6 || Se_B || Se_B_003 || 12:57 || Interrupted || computer || crash
 
−
|-
 
−
| 04-14-16 || 3.283x10^6 || Se_B  || Se_B_005 || 15:57 || 09:37 || 63581.784 || 63509.895
 
−
|-
 
−
| 04-15-16 || 3.37x10^6 ||  Sample D || Sample_D_001 || 14:47 || 08:23 || 236172.264 || 236173.271
 
−
|-
 
−
| 04-19-16 || 3.715x10^6 || Sample B || Sample_B_001 ||15:31||15:18 || 85634.862 || 85624.090
 
−
|-
 
−
| 4-20-16 || 3.802x10^6 ||  Sample C || Sample_C_001 ||15:22||10:19 || 68253.774 || 68232.238
 
−
|-
 
−
| 04-21-16 || 3.888x10^6 || Sample A || Sample_A_001 || 10:22 || 10:37 || 87292.409 || 87268.114
 
−
|-
 
−
|04-25-16 || 4.234x10^6 || Sample E || Sample_E_001 || 11:36 || 10:03 || 80822.406 || 80795.679
 
−
|-
 
−
|
 
−
|}
 
  
−
[[SeRun_01-11-16]]
+
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
  
−
[[SeRun_03-07-16]]
 
  
−
=References=
 
  
−
<references/>
+
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=
 
=MSDS=

Latest revision as of 22:10, 17 May 2019

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?

Se_Overview_PrevMeas

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_ActivityCalc

PAA Selenium/Soil Experiments

LB Se PAA Horse Feed Experiment

Background Signals

PAA_BackGrd_Det_A

Nickel Normalization

LB PAA Nickel Investigation

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

IAC Detector Calibrations

LB April DetB DetA Calibration

Runlists

LB PAA Runlist 4/01/16 - 06/02/16

LB March 2017 Runlist

LB_May_2017_Irradiation_Day

Data Analysis

LB_Feb2017_Se_Investigations

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

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