After installation and before data collection can begin
for the first time, the apparatus must be aligned (Appendix
2) and calibrated (Section 5.). Calibration should
be done for each run. When this process is completed, the incident x-rays
are confined to a 100 x 100 micron beam centered on the sample.
Finally, the relation between channel number on the MCA and the
energy of the diffracted beam, as well as the d-spacing of the diffracting
lattice plane in the sample is established. This must be done independantly
for each of the 4 detectors, when they are part of the experiment.
After a sample is installed, the upper ram is lowered to a fixed position, the spacer block moved into position, and the upper ram raised against the spacer block. This is all done with relative low hydraulic pressure. The lower ram is then raised until the sample is contacted. These hydraulic operations are done with electrical remote controls. A diffraction spectrum is then taken at nominally zero pressure and room temperature.
Although the sequence of steps may vary, depending on the needs of the investigator, the most common sequence is to raise the pressure slowly until the desired pressure is reached, then raise the temperature. At many points during this procedure, the process is halted and a data set taken; data is normally collected for 300 seconds. As the lower ram is raised; the cell assembly is compressed, raising its center; hence, the Z-position of the pedestal must be moved to "follow" the sample. In addition, the sample may be temporarily "lost", so the pedestal must be moved in Y and Z to try to place the center of the sample in diffracting condition. A routine exists to oscillate the pedestal up and down (or in other directions, if desired), to spread the diffraction over a larger area while maintaining precise diffraction conditions. This is useful if the sample is particularly granular.
The pressure-temperature path depends on the needs of the particular experimenter. After the final pressure and temperature are reached, the sample is usually "quenched" (rapidly cooled by switching off the power), and the pressure lowered. As the cell deforms plastically upon pressurization, the depressurization stage is frequently the most difficult; it must proceed slowly (1-4 hours), and "blowouts" are possible. The exact cause of these blowouts is not certain, but it may be due to the inability of the gaskets between the anvils to hold the cell in as the anvils are withdrawn.
In 2000, the VMS computer was retired and the programs ported to a PC. In 2002, an EPICS control system was adapted to the X17 environment, and the control software completely rewritten. The CAMAC is used to house the XIA digital signal processor, and is also used to run the E500 motor controllers. EPICS itself runs on a Motorola-driven card in the VME crate; the operating system is called vxWorks. When the VME crate is booted, the various initialization files are downloaded from another computer, currently a MacIntosh G5 running system 10.3 - a variant of Unix.
Fill the detector with liquid nitrogen. It takes about 15 liters and about 24 hours to cool down completely. For best results, don't let the detector ever warm up. Insert the hose from the 25 liter nitrogen Dewar into the opening at the top of the detector cryostat. The 25 liter Dewar needs to have about 3 PSI internal pressure, which it will develop in about 12 hours if all valves on it are closed. If you are in a hurry, you can pressurize it with the tube from the nitrogen gas bottle inside the hutch.
In the hutch, there are two racks which should be on. Each of the following items should be left on, but you should check to make sure: In the left-hand rack (rack 1, from bottom to top):
In the right-hand rack (rack 2), from bottom to top:
Inside the hutch, but outside the racks, turn on the Elmo and Spot camera power supplies, the D-DIA Gauges power supply, and the Canberra NIM bin on top of the hydraulic system.
The X-17 CAMAC crate and the Linux PC (in the X17B1 area) are normally left on all the time; check that they are on. Also, check that the aperture switches are OFF.
All motors have individual power/enabling switches. All those you do not plan to use should be off.
Each stepper motor is driven by a motor controller module. Most of them are located in the several driver chassis. Some of these chassis are located in the right-hand electronics rack, and others (those for the side station) are located in a short rack near the double door.
Motors 1, and 2 require 2000 steps per revolution, while the rest require 1000 steps (see table A1 in the Appendix). The number of revolutions per user unit (mm or degrees) depends on the mechanical stages and varies from motor to motor. The number of steps per user unit is defined in the motors template file and can be displayed using all in the individual MEDM motor window.
Because it is very important that a motor not be driven accidentally, there are several levels of safety. Each motor or motor bank has switches to enable and control its power. If the motor is not enabled and/or not powered up, the computer may try to drive it, but the motor will not move. In this case, knowledge of the motor position will be lost, and the motor will not move. For motors 11 and 12, there are brakes which must be off for the motor to be driven.
This program creates and/or copies the necessary files to the directory in which you will save your data. Complete directions are in the Documentation directory of drive D: on the server. As of September, 2002, this is mapped as drive P: on the SAM computer (and all other computers at the beam line). This is still true as of March, 2006.
From the server, go to the current directory (create it if it doesn't exist using styles shown analogous to the existing directories). Click on the Startup icon, which will load the IDL Runtime version of Startup. Follow the on-screen directions. There are five buttons at the bottom of the window. Pressing the first one displays the information which has been entered. If there is missing data, you will be notified. Pressing the second one will display and print the information on a letter-sized sheet on the laser printer. The third one will print the label. Check these, and if they are correct, then press the fourth button, which will update the PVs which were set by the Startup program. The fifth button adds a record to the Rundata.log file and exits. If you made a minor mistake, you can edit the label file (RUNLABEL.PRN) and then print it by entering COPY RUNLABEL.PRN LPT1: at the command prompt of the server computer (be sure to include the colon!). Go to the Experiment Information window of the main MEDM control panel, and check that all the lines are correct. Operator Name should have the IDs of all the experimenters; Experiment Title should be a label which doesn't change for the entire run (i.e. for all the files in the current subdirectory). Experiment Comments 4 and 5 should be the chemistry and phase information entered in Startup. Experiment Comments 1, 2, and 3 are there for information which changes for each datafile; Experiment Comment 1 should be a brief label of a specific file (e.g. "Calibration using NaCl", etc).
Problems with getting the detection system to work is frequently due to unexpected changes in the switch settings.
Motor Driver Module for motors 17-24 (this is an incomplete copy of John's box)
Main Power :ON
Motor Driver Module for motors 1-8 (John's box)
Main Power :ON
Bank Power: both ON
Brakes: ON (switches down, lights off)
Individual power switches: OFF
CAMAC Crate: ON
4 push-button switches (from left to right): IN, OUT, OUT, IN
I/O Patch Panel no switches
Display Module no switches
2.4.3 DATA COLLECTION: CAMAC CRATE
We now have a 4-channel DSP which will have the equivalent of 4 DSA2000s. It is in the CAMAC crate, and has no controls. The CRATE must be on.
HIGH VOLTAGE POWER SUPPLY inside Canberra NIM bin
-300 volts for the 13 element detector, +500 volts for the single element detectors
1. Log on (§3.1.1)
2. Determine the directory in which you wish to store your data (§3.1.2).
3. Run Startup. This program will create the necessary files in your directory by asking you several questions about your run, including sample, cell design, etc. By default, you don't have to copy any files into this directory, unless you wish to use the STANDARD.EDF and STANDARD.HKL files OTHER than the ones used by the previous experimenter. You can obtain a copy of the instructions for running Startup by printing STARTUP.PS.
4. Load the SAM85 program by typing SAM85CON (SAM85 Console, as opposed to SAM85 Win, under development). The list of commands in SAM85 are given in section 3.5 (brief description organized by function), and 3.6 (alphabetical list of all commands). You will be put into Primary mode, which is the only mode from which you can write data files, enter titles, etc. Each subsequent loading of SAM85CON will be in secondary mode.
A complete explanation of NT operations is beyond the scope of this manual. For the completely green user, a few simple steps will put you in operation.
You need to log on using the MPI guest account on the MPI domain. If you are unsure, press Ctl-Alt-Delete to bring up the Task Manager, which will show the current account. If it is not MPI/MPI, log off and log back on to that account, using the usual MPI password. This account is authenticated by the SBMP90 server at Stony Brook, so if the network is down, you will have trouble. The correct prompt is G:\SAM85_PC>
After you have logged on, you need to create a subdirectory to store your data. Because the data will be later archived on a CD, and for maximum compatibility with other users, there are certain standards you should use in creating directory names and filenames. The ISO 9600 standard for filenames can be accessed by DOS, Windows, Mac OS, OS\2, and Unix; therefore we use this standard.
ISO 9660
The requirements for the ISO 9660 are similar to the so-called DOS 8.3 structure - that is, a filename using 8 or fewer characters, followed by an extension of 3 or fewer characters. The extension may have 0 characters (such as the EDF. file). The character set consists of capital A to Z, digits 0 to 9, and the symbols ! " % ' ( ) and _. Other ISO 9660 characters cause problems in DOS and perhaps other OSs, so they should be avoided: , = * + - . / : ; < > ? and space.
The current directory will be shown by the prompt. It is easiest to view directories using the Windows Explorer.
All the previously created data sets and directories used for data files are listed sequentially in the file RUNDATA.LOG. If you wish to search for a particular experiment, enter FIND "text" RUNDATA.LOG from the G:\SAM85_PC directory (or FIND "text" G:\SAM85_PC \RUNDATA.LOG from any other directory). The directory structure we have selected has the following characteristics
Directory Level 1
Note: Because of the many types of mixed equipment, we have eliminated the equipment level, and go directly to the next level (formerly 2).
The first level is a broad sample type. It may be very general (e.g. OXIDES), or may be quite specific (e.g.MgSiO3pv):
CARBONAT (carbonates)
CASIO3PV (CaSiO3-perovskite)
CLAYMINS
CO2SIO4A (Co2SiO4 - alpha phase)
DIAMOND (including cBN)
FE2SIO4A (Fe2SiO4 - alpha phase)
FE2SIO4G (Fe2SiO4 - gamma phase)
FESIO3PY (FeSiO3 - pyroxene)
FE_FESI
GARNET (including pyrope and majorite)
HYDROXID (hydroxides)
METALS (including alloys)
MG2SIO4A (forsterite)
MG2SIO4B (wadsleyite, "beta")
MG2SIO4G (ringwoodite, "gamma"
MGSIO3IL ("ilmenite" phase)
MGSIO3PV ("perovskite" phase)
MGSIO3PY (pyroxene phases)
MISC
MNTIO3
NACL
OXIDES
PEROVSKI (other perovskites)
PYROXENE (other than Mg-Fe)
SILICA
SPINELS
SULFIDES
TEST
Directory Level 2
Subsets of level 2. Examples include:
ABG (a-b-g Mg2SiO4 under MG2SIO4)
ALSPINEL (aluminate spinel, under SPINELS)
ALUMINA (under OXIDES)
ANTIGORI (under CLAYMINS)
BRUCITE (under HYDROXID)
CAGE03 (under PEROVSKIT
CALIBRAT (under TEST)
FE_FEO (under OXIDES)
MGO (under OXIDES)
MGO_BN (under OXIDES/MGO)
PERIDOTI (under MISC)
PORTLAND (under HYDROXID)
ZNTE (under MISC)
There is a complete list in Appendix 4.
This depends on the previous series. For some, such as ABG, it will be simply identify the run number, e.g. ABG_01, ABG_02, ... ABG_23. For others, such as ALSPINEL, it will identify which aluminate spinel or carbonate is being measured.
Filenames
The requirements for filenames are somewhat more stringent than the names for directories. First, directory names can be changed later fairly easily, but filenames cannot. Second, several programs require certain characteristics to work properly. Finally, if filenames are reused, then old files can be accidentally overwritten.
The filenames appropriate for this use are best explained by example. The first three characters define the material - e.g. MGO for MgO, GAR for garnet, etc. The next two characters are the two-digit number identifying the run - e.g. GAR12 for the 12th garnet run. The standard extension for energy dispersive data files created by the MCA program is a 3-digit sequence number (e.g. .023). The Bruker CCD detector uses the same filename rules. For all other files associated with a particular spectrum, the above 8 characters are concatenated into an eight character filename, with an extension dependent on the use of the file. For example, the 23rd spectrum for the 12th garnet run will have:
EDS data file GAR12.023
CCD data set GAR12.023
Header file* GAR12023.HDR
Imaging Plate GAR12023.IMG
IP information GAR12023.INF
motor scan file GAR12023.SCN
*Hardware information collected at the same time as the data. Same as the first 24 lines or so of the old *.MCA file, which is no longer used.
Table VI Logging output file (filen.LOG)
date & time | EMF T EMF T anvil tcs V I W Poil LVDT1
95, 2, 2, 5,39, 8, 0, 12.084, 704.1, 0.001, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.20, -2.170
95, 2, 2, 5,39,20, 0, 12.084, 704.1, 0.002, 0.0,-174.8,-180.8, 4.06, 13.58, 55.13, 268.30, -2.170
95, 2, 2, 5,39,32, 0, 12.086, 704.2, 0.002, 0.0,-174.8,-180.8, 4.06, 13.58, 55.13, 268.30, -2.169
95, 2, 2, 5,39,44, 0, 12.086, 704.2, 0.002, 0.0,-174.9,-180.7, 4.06, 13.58, 55.13, 268.10, -2.170
95, 2, 2, 5,39,55, 0, 12.087, 704.2, 0.001, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.10, -2.169
95, 2, 2, 5,40, 7, 0, 12.085, 704.1, 0.001, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.10, -2.170
95, 2, 2, 5,40,19, 0, 12.086, 704.2, 0.001, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.10, -2.169
95, 2, 2, 5,40,31, 0, 12.086, 704.2, 0.002, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.10, -2.169
95, 2, 2, 5,40,43, 0, 12.086, 704.2, 0.002, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.10, -2.170
95, 2, 2, 5,40,55, 0, 12.088, 704.3, 0.002, 0.0,-174.8,-180.8, 4.06, 13.58, 55.13, 268.10, -2.170
95, 2, 2, 5,41, 7, 0, 12.086, 704.2, 0.002, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.10, -2.169
95, 2, 2, 5,41,18, 0, 12.086, 704.2, 0.002, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.20, -2.169
95, 2, 2, 5,41,30, 0, 12.084, 704.1, 0.002, 0.0,-174.9,-180.8, 4.06, 13.58, 55.13, 268.10, -2.171
95, 2, 2, 5,41,42, 0, 12.086, 704.2, 0.001, 0.0,-174.9,-180.7, 4.06, 13.59, 55.18, 268.30, -2.169
95, 2, 2, 5,41,54, 0, 12.084, 704.1, 0.001, 0.0,-174.9,-180.8, 4.06, 13.59, 55.18, 268.20, -2.169
95, 2, 2, 5,42, 6, 0, 12.084, 704.1, 0.002, 0.0,-174.8,-180.8, 4.06, 13.59, 55.18, 268.10, -2.170
95, 2, 2, 5,42,18, 0, 12.085, 704.1, 0.002, 0.0,-174.9,-180.8, 4.06, 13.59, 55.18, 268.30, -2.169
95, 2, 2, 5,42,30, 0, 12.086, 704.2, 0.001, 0.0,-174.9,-180.8, 4.06, 13.59, 55.18, 268.30, -2.169
95, 2, 2, 5,42,41, 0, 12.087, 704.2, 0.002, 0.0,-174.9,-180.8, 4.06, 13.59, 55.18, 268.30, -2.160
95, 2, 2, 5,42,53, 0, 12.087, 704.2, 0.002, 0.0,-174.9,-180.8, 4.06, 13.59, 55.18, 268.10, -2.170
95, 2, 2, 5,43, 5, 0, 12.088, 704.3, 0.002, 0.0,-174.8,-180.8, 4.06, 13.59, 55.18, 268.30, -2.169
95, 2, 2, 5,43,17, 0, 12.088, 704.3, 0.001, 0.0,-174.9,-180.8, 4.06, 13.59, 55.18, 268.10, -2.169
95, 2, 2, 5,43,29, 0, 12.090, 704.4, 0.002, 0.0,-174.9,-180.8, 4.06, 13.59, 55.18, 268.10, -2.170
95, 2, 2, 5,43,41, 0, 12.090, 704.4, 0.002, 0.0,-174.8,-180.8, 4.06, 13.59, 55.18, 268.10, -2.169
95, 2, 2, 5,43,53, 0, 12.093, 704.5, 0.002, 0.0,-174.8,-180.8, 4.06, 13.59, 55.18, 268.20, -2.170