National High Magnetic Field Laboratory, NHMFL
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User HintsExperience has demonstrated a number of steps users can take to increase the efficiency and benefits of their pulsed magnet visits. • Do work safely! As part of Los Alamos National Laboratory users are expected to follow our rules for safe work practices. Eye protection is required for all cryogenic transfers and a safety video will be provided for all first time users. So, be prepared to work safely at LANL.• Get in touch with your contact. Before you arrive, 'walk through' the experiment (by phone) with your designated Los Alamos contact (who is assigned to you after your NHMFL request is approved) to insure you both understand what is needed and how theexperiment will be done. • Be prepared. Prior preparation is the single most important factor.Precious days can be lost doing sample mounting or characterization that could have been done at the user's home institution. • Determine the required equipment. Obtain a mutual understanding with your contact about what instruments and equipment are needed and the time required. (i.e. Lock-In, resistance bridge, temperature controller, frequency synthesizer, pre-amps... • If in doubt, bring it. That is, bring any specialized equipment or software needed for data acquisition, analysis or transfer (e.g., to the home institution), disk drives, sample prep devices, jigs, signal filters, etc. • If possible set up an FTP site at your home institution. A week of magnet time generates between 30 and 120 Mb of data. Zip disks are used widely and we will burn a CD for you with your data on it. Since magnet time usually ends on Friday at 5:30 PM, FTP sites have proven to be the most convenient. CD's often take an hour or two to compile the data and burn the CD therefore it is difficult to get a complete data set burnt on the final day of magnet time. Often CD's are mailed to users after their departure. All common formats are supported: ISO 9660, Macintosh, Windows Joliet, multi-session CD-ROM XA. • Coordinate your experiment. Decide with your contact about who will do what, especially in the case of experiments involving a team of outside people. • Have an experimental contingency plan in case your delicate or elaborate first plan encounters problems. Or, try a test experiment first, to verify assumptions about the setup of your primary experiment. • Pre-mount your samples to the extent possible. Sample holders can be mailed in advance for magnetotransport experiments in the 60 T Long pulse and 60 T Short Pulse magnets. • Understand that pulsed field experiments are different from DC field experiments. For example, the dB/dt of the capacitor driven magnets produces about 10 mV/mm2 in areas normal to the field. Eddy current heating can alsooccur. • Shop work by a professional machinist is possible, with adequate notification and planning (i.e. drawings). The NHMFL is committed to provide the advertised fields, temperatures, pressures, volumes, data acquisition, etc., as well as professional advice and assistance as needed. Collaborations with NHMFL or other Los Alamos staff are useful in allowing measurements to continue in the user's absence. (Routine followup experiments do not require a new request form.) For many years Dr. Simon Foner collaborated with users on pulsed field experiments at the Francis Bitter National Magnet Laboratory, MIT. His thoughts on the subject remain relevant today: "Some general observations are: Almost all the user experiments developed as extensions of research carried out with the lower DC field facilities at the laboratory. The DC research acts as a catalyst for extension to a higher field. With our DC facilities, the user can readily take control of the magnets with a minimum of instruction. This is not true of pulsed field facilities where the experiments require special knowledge and techniques. Safety is a major concern. Unless the user dedicates substantial time on location, local support staff are needed for both design of experiments and for carrying out experiments. Thus, operation in a user mode is largely done in collaboration with the user." Physica B 155 (1989) 18-22.
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