Welcome to the New Mexico Geochronology Research Laboratory!

_images/NMGRL_logo.png _images/RossLabs_logo.png _images/NMT_logo.png

Lab Procedures Guide

Various Lab procedures are explained below.

Loading CO2 Samples

Please read this guide carefully and follow the provided checklist

CO2 Laser Loading Instructions for the Argus VI

This section describes the procedure for loading a CO2 laser tray on the new NMGRL extraction line.

You will need: torque-wrench, flat-head screw driver, vice grip pliers, 4mm hex wrench, tweezers, new KBr cover slip, new 4.5 in. copper gasket

  1. Confirm that multiple-runs has finished.
  2. Take note of the pressure in the roughing, minibone, and microbone system. Roughing and analytical pressures should be approximately 10-7 to 10-8 and 10-9 to 10-10 torr, respectively.
  3. Configure values for breaking vacuum. Close and lock pneumatic valves G (CO2 laser to roughing), A (CO2 laser to microbone), and F (CO2 laser to bone). If necessary, close the manual valve between the diode laser chamber and the roughing line (Fig. 1). CO2 chamber is now isolated from UHV and roughing systems.
  4. Place protective metal plate on CO2 laser chamber window.
  5. Slightly loosen the two bolts that connect the CO2 laser base to the CO2 laser stand. Bolts should remain engaged in their nuts. Slide the CO2 laser back on the rail until you can freely access CO2 laser chamber. The base of the laser will hang off of the laser rack. Retighten the bolts (Fig. 2).
  6. Loosen the heating tape on the CO2 laser chamber so that the heating tape dangles beneath the CO2 laser chamber.
  7. Unbolt the CO2 laser chamber window.. Roughing, minibone, and microbone pressure should not change. Set the CO2 laser chamber window on a fresh piece of Al-foil on the CO2 laser cart. Remove the copper gasket using a vice grip wrench. Place a fresh copper gasket on the knife-edge seal of the CO2 laser chamber. Never leave the knife edge exposed for long periods. The three, free-floating posts on the inside of the laser chamber are used to stabilize the KBr cover slip. These can be kept in their position or set aside for easy access. Dispose of the KBr cover slip in the radiation waste bin in the radiation room. Remove the “used” laser tray using tweezers and place it back in the radiation room.
  8. Using tweezers, carefully place the “new” laser tray in the CO2 laser chamber so that the notch at the top of the tray is closest to the extraction line (Fig. 3). Using tweezers, place a new KBr cover slip on the copper tray.
  9. Place the CO2 laser chamber window on top of the CO2 laser chamber base. Tighten the CO2 laser chamber bolts using the torque wrench and a “wagon wheel” pattern (Fig. 4). Tighten the CO2 laser chamber in four increments (40, 70, 100, and 120 in/lbs). CO2 laser chamber is now ready to be evacuated.
  10. Turn off roughing ion gauge (lower switch on gauge display) and roughing turbo pump (far right button on “shared roughing” pump controller.)
  11. Unlock and open pneumatic valve G (CO2 laser to roughing). Atmospheric gas is now in the roughing section of the extraction line. Backing pressures of the roughing section (bottom two displays on the roughing gauge) will briefly increase (~3-4 torr) and then decrease to approximately 10-1 torr.
  12. Turn on the roughing turbo pump. Initial current will be between 2 and 3 amps. Within a couple of minutes the turbo current should decrease to ~0.2 amps when back to full speed or 1500 hz. Turn on roughing ion gauge. Pressure should be between 10-5 and 10-6 torr and decreasing. Lock pneumatic valve G in the open position. If the turbo pump is pulling too much current and/or the pressure is significantly higher than expected values, this may indicate a leak in the CO2 laser chamber. Close and lock valve G (CO2 laser to roughing) and repeat steps 6 through 11.
  13. Rewrap the sides of the CO2 laser chamber with the heating tape (Fig. 2). Fasten thermocouple ring to laser chamber and insert thermocouple. Make sure the thermocouple and heating tapes are plugged in. If necessary, place heating tape over the cold-finger. Wrap the CO2 laser chamber and cold finger with aluminum-foil.
  14. Open Bakedpy on the pyValve/pyCO2 computer. Using the drop-down menu in the control panel, select “CO2-8hour.cfg”, then hit execute. Bakeout controllers 2,3, and 4 should begin heating and temperatures will slowly increase on the time vs. temperature plot at the bottom of the Bakedpy window. (NOTE: Sometime heating tapes are switched for various reasons; controllers 2,3, and 4 will not always be used).
  15. Put tools away and clean up the workspace!
procedures/images/CO2_Figure1.png

Figure 1: Picture of diode laser chamber showing location of valves. For baking the CO2 chamber, close the valve between the laser chamber and roughing system.

procedures/images/CO2_Figure2.png

Figure 2: Picture showing the configuration of CO2 system for loading laser trays and baking. Base of the laser will hang off the laser cart. CO2 laser has heating tapes in correct orientation for baking.

procedures/images/CO2_Figure3.png

Figure 3: Proper orientation of laser tray in CO2 laser chamber.

procedures/images/CO2_Figure4.png

Figure 4: Bolting pattern for CO2 laser chamber.

CO2 Stage Calibration

  1. Move the laser to the center hole.
  2. Select the correct stage map e.g 221-hole
  3. Select pychron-auto as the calibration style
  4. Hit Calibrate

Pychron will now automatically find up to five calibration holes. The calibration holes are specified on the third line of the stage map file e.g 221-hole.txt. The calibration holes should be the N,E,S,W, and center holes.

Using the calibration holes Pychron calculates the center position and rotation of the tray. With an accurate calibration, Pychron will then move to each hole and determine a corrected position. This will take a few minutes.

Autofocus

Pychron has an auto focus feature that can produce a very sharp image. Configuration allows you to use various alogrithms to calculate the focus measure of an image. I find the Laplace filter with ~50% zoom produces a nice result. Autofocus is actual a misnomer in this case. What is really happenig is called passive focus. The focus measure is calculated by applying a mathematical filter the the image. These filters are used for example to calculate the gradient between adjacent pixels. Theoretically maximizing the gradient yields the most focused image. For more information see Autofocus

Hit Autofocus to perform an autofocus routine

CO2 Diagnostics

This section describes some questions to ask when debugging the Fusions CO2 Laser System

Start with a clear definition of the Problem

  1. Is Pychron running? Is the CO2 plugin enabled?
  2. Are there any warnings on startup?
  3. When starting does the laser home its beam motor? If so, the progress window will display Homing Beam for a few seconds
  4. Open the laser manager. Is there a view of the sample chamber? Is the use_video preference enabled?
  5. Can you enable the laser? Red lights turn on Fusion control boxes are illuminated.
  6. Do the red lights stay on for only 7 seconds?
  7. Are the emergency STOP buttons depressed?
  8. Is the manual beam blocked in place? Check the knob on the back of the CO2 laser.

UPS Battery Change

Ferrups

See manual.

  1. Set ups to Inverter mode.
  2. Open front panel and disable circuit breaker. This cuts of battery power to the ups
  3. Remove side panels
  4. Disconnect negative battery terminal from the ups
  5. Disconnect positive battery terminal from the ups
  6. Disconnect batteries from one other
  7. Remove strap and plastic dividers, noting orientation for when reinstalling
  8. Remove old batteries
  9. Install new batteries
  10. Install plastic dividers and strap
  11. Connect side A batteries together with a short cable
  12. Connect side B batteries together with a short cable
  13. Connect side A to side B with long cable
  14. Connect positive terminal to ups
  15. Connect negative terminal to ups
  16. Enable circuit breaker
  17. Set UPS to Auto mode

BestPower

Reference Values

Mesh vs Age Error

_images/mesh_vs_age_error.png

MSWD Interval

N Low 95% High 95%
2 0.001 5.024
3 0.025 3.689
4 0.072 3.116
5 0.121 2.786
6 0.166 2.567
7 0.206 2.408
8 0.241 2.288
9 0.272 2.192
10 0.300 2.114
11 0.325 2.048
12 0.347 1.993
13 0.367 1.945
14 0.385 1.903
15 0.402 1.866
16 0.417 1.833
17 0.432 1.803
18 0.445 1.776
19 0.457 1.751
20 0.469 1.729
21 0.480 1.708
22 0.490 1.689
23 0.499 1.672
24 0.508 1.655
25 0.517 1.640
26 0.525 1.626
27 0.532 1.612
28 0.540 1.600
29 0.547 1.588
30 0.553 1.577
40 0.607 1.490
50 0.644 1.433
60 0.672 1.392
70 0.695 1.360
80 0.713 1.335
90 0.728 1.314
100 0.741 1.297
200 0.813 1.206
300 0.846 1.167
400 0.866 1.143
500 0.880 1.128
600 0.890 1.116
700 0.898 1.108
800 0.904 1.100
900 0.910 1.095
1000 0.914 1.090

Constants

Name Value units
1 A 6.2415e18 e-
1 fA 6241.5 counts
1 fA 0.1 mV @10e11 Ohms
1 fA 1 mV @10e12 Ohms
1 fA 10 mV @10e13 Ohms

Typical Mineral Values

Name Min Max
Biotite K/Ca    
Sanidine K/Ca    
Plagioclase K/Ca    
Hornblende K/Ca    
Mol 40Ar/g    

Typical Hardware Values

Name Min Max units
Analytical IG 1e-10 1e-8 torr
Jan Sensitivity CO2 5e-14   mol/fA
Jan Rise Rate 0.75   fA/min
Jan Rise Rate CO2 1.0   fA/min
Jan Rise Rate UV 1.0   fA/min
Obama Sensitivity CO2 8e-14   mol/fA
Obama Rise Rate      
Obama Rise Rate CO2 1   fA/min
Obama Rise Rate Diode 1   fA/min

Extraction Line

_images/annotated_extraction_line2.png

Bone Valves

Name Description
B Bone to Diode Laser
C Bone to Turbo
D Bone to CO2 Laser
E Bone to Minibone
H Obama Inlet
N Bone to Getter GP-50

Minibone Valves

Name Description
I Minibone to Bone
Q Quad Inlet
P Minibone to Turbo
W Outer Pipette 1
X Inner Pipette 1
Y Outer Pipette 2
Z Inner Pipette 2

Microbone Valves

Name Description
K Microbone to Getter D-50
L Microbone to Minibone
M Microbone to Getter NP-10
R Jan Inlet
S Microbone to Inlet Pipette
T Micorbone to Laser
U Microbone to Turbo

CO2 Valves

Name Description
A CO2 Laser to Jan
F CO2 Laser to Obama
G CO2 Laser to Roughing

Spectrometer Ion Pump Valves

Name Description
V Obama Ion Pump
O Jan Ion Pump

Software Layout

_images/new_server_layout.png _images/NMGRL_software_configuration2.png

Bibliographies

Fish Canyon and Intercalibration

  1. Bachmann, O. and Dungan, M. A. Temperature-induced Al-zoning in hornblendes of the Fish Canyon magma, Colorado. American Mineralogist 87, 1062–1076 (2002).
  2. Bachmann, O., Dungan, M. A. and Lipman, P. W. The Fish Canyon magma body, San Juan volcanic field, Colorado: rejuvenation and eruption of an upper-crustal batholith. J Petrol 43, 1469–1503 (2002).
  3. Bachmann, O., Dungan, M. A. and Bussy, F. Insights into shallow magmatic processes in large silicic magma bodies: the trace element record in the Fish Canyon magma body, Colorado. Contributions to Mineralogy and Petrology 149, 338–349 (2005).
  4. Bachmann, O., Oberli, F., Dungan, M., Meier, M., Mundil, R., and Fischer, H. 40Ar/39Ar and U–Pb dating of the Fish Canyon magmatic system, San Juan Volcanic field, Colorado: Evidence for an extended crystallization history. Chemical Geology 236, 134–166 (2007).
  5. Charlier, B. L. A., Bachmann, O., Davidson, J. P., Dungan, M. A. and Morgan, D. J. The Upper Crustal Evolution of a Large Silicic Magma Body: Evidence from Crystal-scale Rb Sr Isotopic Heterogeneities in the Fish Canyon Magmatic System, Colorado. J Petrol 48, 1875–1894 (2007).
  6. Jourdan, F., Matzel, J. P. and Renne, P. R. 39Ar and 37Ar recoil loss during neutron irradiation of sanidine and plagioclase. Geochimica et Cosmochimica Acta 71, 2791–2808 (2007).
  7. Jourdan, F. and Renne, P. R. Age calibration of the Fish Canyon sanidine 40Ar/39Ar dating standard using primary K–Ar standards. Geochimica et Cosmochimica Acta 71, 387–402 (2007).
  8. Lipman, P., Dungan, M. and Bachmann, O. Comagmatic granophyric granite in the Fish Canyon Tuff, Colorado: implications for magma-chamber processes during a large ash-flow eruption. Geology 25, 915 (1997).
  9. Lipman, P. W. and McIntosh, W. C. Eruptive and noneruptive calderas, northeastern San Juan Mountains, Colorado: Where did the ignimbrites come from? Geological Society of America Bulletin 120, 771–795 (2008).
  10. Min, K., Mundil, R., Renne, P. R. and Ludwig, K. R. A test for systematic errors in 40Ar/39Ar geochronology through comparison with U/Pb analysis of a 1.1-Ga rhyolite. Geochimica et Cosmochimica Acta 64, 73–98 (2000).
  11. Renne, P. R., Mundil, R., Balco, G., Min, K. & Ludwig, K. R. Joint determination of 40K decay constants and 40Ar*/40K for the Fish Canyon sanidine standard, and improved accuracy for 40Ar/39Ar geochronology. Geochimica et Cosmochimica Acta 74, 5349–5367 (2010).
  12. Schmitz, M. D. and Bowring, S. A. U-Pb zircon and titanite systematics of the Fish Canyon Tuff: an assessment of high-precision U-Pb geochronology and its application to young volcanic rocks. Geochimica et Cosmochimica Acta 65, 2571–2587 (2001).

BibTex Keys

  1. @article{Bachmann:2002vq,
author = {Bachmann, O and Dungan, M A},
title = {{Temperature-induced Al-zoning in hornblendes of the Fish Canyon magma, Colorado}},
journal = {American Mineralogist},
year = {2002},
volume = {87},
number = {8-9},
pages = {1062--1076}
}

  2. @article{Bachmann:2002wz,
author = {Bachmann, O and Dungan, M A and Lipman, P W},
title = {{The Fish Canyon magma body, San Juan volcanic field, Colorado: rejuvenation and eruption of an upper-crustal batholith}},
journal = {Journal of Petrology},
year = {2002},
volume = {43},
number = {8},
pages = {1469--1503}
}

  3. @article{Bachmann:2005ca,
author = {Bachmann, O and Dungan, M A and Bussy, F},
title = {{Insights into shallow magmatic processes in large silicic magma bodies: the trace element record in the Fish Canyon magma body, Colorado}},
journal = {Contributions to Mineralogy and Petrology},
year = {2005},
volume = {149},
number = {3},
pages = {338--349},
month = mar
}

  4. @article{Bachmann:2007gu,
author = {Bachmann, O and OBERLI, F and DUNGAN, M and MEIER, M and Mundil, R and FISCHER, H},
title = {{40Ar/39Ar and U--Pb dating of the Fish Canyon magmatic system, San Juan Volcanic field, Colorado: Evidence for an extended crystallization history}},
journal = {Chemical Geology},
year = {2007},
volume = {236},
number = {1-2},
pages = {134--166},
month = jan
}

  5. @article{Charlier:2007ii,
author = {Charlier, B L A and Bachmann, O and Davidson, J P and Dungan, M A and Morgan, D J},
title = {{The Upper Crustal Evolution of a Large Silicic Magma Body: Evidence from Crystal-scale Rb Sr Isotopic Heterogeneities in the Fish Canyon Magmatic System, Colorado}},
journal = {Journal of Petrology},
year = {2007},
volume = {48},
number = {10},
pages = {1875--1894},
month = sep
}

  6. @article{Jourdan:2007vi,
author = {Jourdan, F. and Matzel, J.P. and Renne, P R},
title = {{39Ar and 37Ar recoil loss during neutron irradiation of sanidine and plagioclase}},
journal = {Geochimica et Cosmochimica Acta},
year = {2007},
volume = {71},
number = {11},
pages = {2791--2808}
}

  7. @article{Jourdan:2007dm,
author = {Jourdan, Fred and Renne, Paul R},
title = {{Age calibration of the Fish Canyon sanidine 40Ar/39Ar dating standard using primary K--Ar standards}},
journal = {Geochimica et Cosmochimica Acta},
year = {2007},
volume = {71},
number = {2},
pages = {387--402},
month = jan
}

  8. @article{Lipman:1997wm,
author = {Lipman, P and Dungan, M and Bachmann, O},
title = {{Comagmatic granophyric granite in the Fish Canyon Tuff, Colorado: implications for magma-chamber processes during a large ash-flow eruption}},
journal = {Geology},
year = {1997},
volume = {25},
number = {10},
pages = {915}
}

  9. @article{Lipman:2008gs,
author = {Lipman, P W and McIntosh, W C},
title = {{Eruptive and noneruptive calderas, northeastern San Juan Mountains, Colorado: Where did the ignimbrites come from?}},
journal = {Geological Society of America Bulletin},
year = {2008},
volume = {120},
number = {7-8},
pages = {771--795},
month = jul
}

  10. @article{Min:2000vr,
author = {Min, K. and Mundil, R and Renne, P R and Ludwig, K R},
title = {{A test for systematic errors in 40Ar/39Ar geochronology through comparison with U/Pb analysis of a 1.1-Ga rhyolite}},
journal = {Geochimica et Cosmochimica Acta},
year = {2000},
volume = {64},
number = {1},
pages = {73--98}
}

  11. @article{Renne:2010iz,
author = {Renne, Paul R and Mundil, Roland and Balco, Greg and Min, Kyoungwon and Ludwig, Kenneth R},
title = {{Joint determination of 40K decay constants and 40Ar*/40K for the Fish Canyon sanidine standard, and improved accuracy for 40Ar/39Ar geochronology}},
journal = {Geochimica et Cosmochimica Acta},
year = {2010},
volume = {74},
number = {18},
pages = {5349--5367},
month = sep
}

  12. @article{Schmitz:2001tc,
author = {Schmitz, M D and Bowring, S A},
title = {{U-Pb zircon and titanite systematics of the Fish Canyon Tuff: an assessment of high-precision U-Pb geochronology and its application to young volcanic rocks}},
journal = {Geochimica et Cosmochimica Acta},
year = {2001},
volume = {65},
number = {15},
pages = {2571--2587}
}

Computer Names

Mac

To connect from a Mac use the Finder, Go > Connect To Server… (cmd-K)

Enter the address of the computer you would like to connect to.

To file share prepend the address with afp://

afp://pychron.local
or
afp://129.138.12.153

To screen share use vnc://

vnc://pychron.local
or
vnc://129.138.12.153

If a connection is made you will be prompted for a username and password.

Enter the username and password of the computer you are trying to connect to.

Computer Username Address short address Task
Pychron mini pychron 153 pychron.local Extraction Line
Obama iMac obama 137 obama.local Pychron Master
Jan iMac jan 150 jan.local Pychron Master
Diode mini diode 134 diode.local Diode
UV mini uv 132 uv.local UV
CO2 mini argonlab3 133 co2.local CO2
ArgonLab1 iMac argonlab1 138 argonlab1.local Lab computer
ArgonLab2 iMac argonlab2 143 argonlab2.local Lab computer
Argonlab4 mini argonlab4 158 argonlab4.local Database replication, Bakeout
    155   Environmental Monitor
    157   USB server

Windows

Computer Username Address Task
ObamaArgus Thermo 145 Qtegra
JanArgus Thermo 152 Qtegra

To connect to a Windows computer using a remote desktop client such as TightVNC or Chicken of the VNC

Lab Meetings

LabMeeting 1. 1/27/15

Changelog

  • added “Whats New” action. brings user to this doc.
  • added Experiment Columns defaults. [root]/setupfiles/experiment_defaults.yaml
  • fixed displaying irradiation holder
  • added auto saving of experiment queues. Auto saves to a .bak file whenever values change or run added
  • added SampleImageTask
  • added notes to irradiation levels
  • added task switching to Browser pane

Go Over

  1. Whats New
  2. Experiment Columns
  3. Auto save experiments
  4. Notes to Irradiation levels. Info/Chronology Panes
  5. Conditional edit/view

Indices and tables