Rules for using BT-1
DO NOT ENTER THE DETECTOR AREA WHEN THE BEAM IS ON
- Information board and log book.
- You MUST write the sample composition along with your name(s) and telephone number(s) on the white board. Also fill out all information requested in the BT-1 log book and on a BT-1 sample tag.
Add your samples to the Sample Tracking App and print a barcode. See an instrument scientist if you are unable to do so.
- Shutter/Collimation operation.
- Press the desired collimation usa-button and wait while the drum rotates to the desired point. Do not enter the sample area.
- Press the green 'close' usa-button to close the beam
- Remove and take the shutter key when working in the beam path.
- Monochromator/Collimation selection.
- Trained persons may change the monochromator settings.
- Sample position.
- The beam is 5/8" wide, and is focused to a 2" height at the sample position. To check your sample positioning with the neutron sensitive camera see an instrument scientist.
- Scan range, step size, and time.
- The default scan range of 3-13 degrees 2theta (1.3-11.3 for Ge311) with a step size of 0.05 is highly recommended so that each data point is counted in two different detectors.
- Sample checking.
- If you are unsure of the quality of your sample, run a quick scan (60' collimation, range 5-10 degrees, 0.1 degree steps, 10 sec count).
- Sample changer.
- Do not attempt to mount the 6-position automatic sample changer without instruction/approval of someone qualified in its use.
- The ICP command next advances to the next sample position
- Unloading Samples.
- Survey your sample before removing it from the instrument area. All V sample cans are to be stored in the BT-1 cabinet when not in use.
- Log sample cans to be removed from the BT-1 area - use the NCNR Samples Tracking App or contact someone who as access to it
- Never open cans in C100.
- Health Physics must clear irradiated powder samples before they are removed from cans, but select few have training to access the Hot labs if required: see your instrument contact.
DO NOT ENTER THE DETECTOR AREA WHEN THE BEAM IS ON
Sample Handling Procedures
This outlines recommendations for use BT-1 and storage and handling of samples. Exceptions from these recommendations will be made for experiments with unusual needs. All experiments at BT-1 will have a NIST employee either as an active participant or as a local coordinator. It is the responsibility of this NIST employee to ensure that users are properly trained, and to ensure that NIST procedures are followed with respect to sample handling.
Prior to experiments
BT-1 users are strongly recommended to evaluate the potential activation for their material using this tool or by contacting Health Physics.
See a BT-1 scientist or Juscelino Leao for vanadium sample containers. Requests for cans made at the last minute may not be accommodated.
A BT-1 Sample Tag should be filled out when the sample is loaded into the container. The sample tag should be attached to the sample, or to the outside of a cryostat, furnace, etc, when the sample is not in the instrument.
Add samples to the NCNR Sample Tracking App, print a barcode, and record its location through out its stay in the NCNR. See an instrument scientist for help.
It is NCNR policy that all samples must be recorded in the log book as well as the instrument monitor (mrat) reading. For proprietary measurements, an approximate empirical chemical formula may be used.
The whiteboard must be updated to show the experiment, the name and phone numbers for an emergency contact and the names and institutions of all experimenters. The BT-1 sample tag(s) are to be hung on the whiteboard or sample environment equipment, when sample(s) are loaded in BT-1 for measurement.
A survey must be performed before the sample is removed from the instrument.
Until such time as appropriate facilities are available, all irradiated powder samples must be checked by Health Physics before they can be removed from their containers. Since samples are frequently unloaded by someone other than the person who loaded the sample, if special precautions or non-ambient conditions are needed for unloading the sample, note this on a pink sample tag or other obvious indicator.
The local contact is responsible for assisting users with unloading samples, clearing samples through Health Physics and shipping samples. When users must leave NIST without their samples, either because their experiments are not complete or the materials are neutron activated, the user must complete a BT-1 Sample Shipping Form and either provide a Material Safety Data Sheet (MSDS) or certify their sample is not hazardous (flammable, toxic, etc.). Samples without shipping forms may not be shipped.
Sample containers are to be stored after experiments in the unlocked cabinet adjacent to BT-1. If this is not possible because the sample requires special storage conditions, this should be discussed with a BT-1 instrument scientist prior to the experiment and the location of the sample container noted in the Sample Tracking App. Likewise, if the sample and container will be used on another instrument, the App must also be updated and the container be returned after the measurement.
Controlling the Instrument
The instrument control program IICPP can be invoked from the command line in any directory (type: 'icp' and hit 'return'). Commands that control the instrument hardware can only be executed when entered from the first session of ICP, but other sessions can be opened to check things like the sequence or how long the sequence will run.
Buffers (I-buffers 'increment'-buffers for scanning motor angles in steps for BT-1) and sequences of events can be edited using the 'prepare' command from the same directory that ICP is running in.
- Set the temperature of magnet device: tdev, hdev to the required controller - follow instructions on screen
- Ensure that the monochromator is correct, save the monitor rate if needed (mrat/s -20)
- Use 'prepare' to edit buffers and sequences as needed. Sequences can also be listed in a file with one line per command.
- use the following commands to run the most appropriate action:
- prs : print the run sequence
- howlong/rs : determine how long the sequence will take assuming that the monitor rate is correct and saved
- howlong i2-5 : determine how long buffers 2 through 5 will take
- howlong/f filename : determine how long filename sequence will take to run
- ri# : run i-buffer number #
- rs : run sequence
- rsf filename : run the sequence defined in filename
The run can be paused by pressing 'ctrl-z' : collection will paused after the prefactor number of counts are acquired. 'ctrl-z' resumes.
Emergency Abort press 'ctrl-c'
Additional useful commands
Notes on using PREPARE
More options become available in the GUI if you choose 'simple' 'temperature control' or 'magnet control'. There are some known strange behaviors in Prepare, so please use the simplest mode possible!
- Comments : the first 5 characters are the file name (with a ### number iteratively added)
- A3 is the sample table: it usually does not need setting
- A4 defines the detector bank start (beg), step (inc) and end in 2-theta, in NPTS number of points.
- T0 : The target data collection temperature. The meaning of the value depends on the temperature controller. Most NCNR controllers use Kelvin, but the high temperature furnace uses Celsius. This value is ignored if 0 or if the 'T-' flag is set, or you dont have a controller set.
- Inc-T : An increment to be added to the temperature at each data point. The is almost always 0.0 at BT-1.
- WAIT : This value specifies a maximum delay (in minutes) to be applied any time the temperature goes outside the range T0+/- ERR. As soon as the temperature is within the range, the run resumes. Thus, there is usually no penalty for making this number large.
- ERR : This determines the maximum error in the temperature setting before introducing a delay (if Wait is non-zero). You probably don't want this number to be too small, as you will lose data collection time if random fluctuations bring the sample temperature outside the range.
- Hld0 : This value specifies a delay (in minutes) to use before starting the scan. This delay occurs after the set-point temperature has been reached, so this is commonly used to allow time for a sample to equilibrate after changing temperature.
- Hld : This is a delay applied before each point. Always leave this value as 0; any other value just wastes data collection time.
- Field : This invokes a menu for setting magnetic field conditions. If Copying buffers ENSURE this has the values you want!!!!
- Monit : This value along with Prefac and M-typ sets the data collection time for each data point (see below). If M-typ is Time, Monit is a value in seconds. If M-typ is Neut, Monit is a number of monitor counts.
- Prefac : Each measurement is repeated Prefac times, and if Prefac is 4 or greater, the measurements are checked for statistical consistency and additional measurements are made until consistent measurements are obtained. Note that the actual data collection time is determined by Monit*Prefac
- M-Typ : The monitor type can be either Time or Neut. If Time is selected, data points are counted for fixed time periods of Monit*Prefac seconds. If M-typ is Neut, data points are counted for fixed incident beam flux and Monit*Prefac monitor counts.
- AUTOMON : This brings up a menu that can be used to estimate the Monit value needed so that a run will finish at a given time, or run for a certain period.
Always 'UPDATE' before switching buffers or the changes are not kept!
BufOps allows other buffer operations to be performs. Useful ones are:
COPY n1[-n2],m (Copy buffers n1 to n2 into m, m+1, ...) i.e. 'copy 1,2' copies buffer 1 to 2.
Notes on setting up temperature devices
- tdev : input a temperature device that you wish to control and is plugged in to the computer (e.g. 25 pin 'temp' cable to Lakeshore)
- most Lakeshore controllers are option '10'
- Choose sample and control channels
- Check communications and read temperature 'pt'
- Ensure heater is on at the Lakeshore controller (other users may have turned it of if only requiring base temp.)!
Notes on setting up the 7-T magnet
- hdev : choose "Superconducting Magnet with no persistence switch" option; "Oxford controller" ; 0.0778 A/G; 90 A limit