Rocky Mountain 900 MHz Test Library

Our facility has undergone numerous tests during the installation process. As a result of these tests we have great confidence in the performance of the system. In this spirit, and as a service to the NMR community, we are providing all of the test data obtained for the system.

We hope that this will allow users to directly compare their systems to ours, and get an idea of the quality of the data that they can hope to collect at our faclity.

Disclaimer: Some of the tests presented here are extremely dependent on sample and experimental conditions. These may not be completely reproducible on other systems and so comparisons should be made with care. In addition, some tests exhibit statistical deviations from the mean value, and should therefore be run several times. In these cases we have included only the results that represent the average, rather than the extreme cases.

  1. Magnet
  2. Hardware Testing
  3. Shim Systems and VT Unit
  4. RF Amplifiers
  5. RF Stability
  6. Lock
  7. Receiver System
  8. Gradient Hardware
  9. Probe Specifications

  1. Magnet

    1. Magnet Drift Rate
      Drift of main field of the magnet
      Spec: less than 10 Hz/hr
      Actual: 2.49 Hz/hr

    2. Liquid Helium Hold Time
      Spec: 60 days
      Actual: 60 days

    3. Liquid Helium Boil Off Rate
      Spec: less than 400 mL/hr
      Actual: 265 mL/hr

    4. Liquid Nitrogen Hold Time
      Spec: 14 days
      Actual: 14 days

    5. Liquid Nitrogen Boil Off Rate
      Spec: less than 1200 mL/hr
      Actual: 735 mL/hr

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  2. Hardware Testing
    1. RF Homogeneity
      Conditions:
      • perform 100 experiments separated by repetition time.
      • increment pulse width by 1/10th of 90 starting at 1/10 of 90.

      Specification: intensity ratio for 810°/90° > 65%
      Actual: 71.87%

    2. Cancellation Test
      Conditions:
      • perform 4 one transient, 4 two phase cycle (x, -x) cancellation, and 4 four phase cycle (x, y, -x, -y) cancellation experiments
      • use 90 degree pulses, 4 steady-state pulses, normal repetition time

      Specification: Average total height (positive plus negative deviation) of each set of cancellation experiments (two phase cycle and four phase cycle) less than 1.0% of single transient peak height
      Actual: less than 1.0%

    3. Quadrature Image Rejection Test
      Conditions:
      • 4 single transient and 4 four phase cycle experiments
      • set water off-resonance by 70 Hz

      Specification: quadrature images less than 0.2% on single transient experiments and less than 0.05% on four phase cycle experiments.
      Actual: No quadrature images due to VNMRS receiver

    4. Small Angle Phase Test
      Conditions:
      • perform single transient experiments with pulse phase incremented by 10 degrees from 0 degrees to 360 degrees
      • phase all transients identically

    5. Pulse Stability Test
      A 90 degree pulse will be applied to a sample of doped H2O/D2O (linewidth < 7 Hz), nonspinning, and the amplitude of the resulting signal will be measured. This experiment is repeated 20 times with a sufficient time between experiments to insure complete relaxation. The standard deviation for the amplitude is calculated. The experiment is repeated with a 30 degree pulse and a 1us pulse. Matched line-broadening is utilized.

    6. Pulse Ideality Test
      Conditions:
      • perform six single transient experiments separated by repetition time composed of pulses of same phase each separated by 1 us
      • first experiment 1 pulse of 20 us
      • 2nd experiment 10 pulses of 2 us each
      • 3rd experiment 20 pulses of 1 us each
      • 4th experiment 25 pulses of 0.8 us each
      • 5th experiment 50 pulses of 0.4 us each
      • 6th experiment 100 pulses of 0.2 us each

      Specification: Ratio of peak height from 6th experiment to peak height of 1st experiment will be greater than 0.80
      Actual: 0.8407

    7. Glitch Test
      Conditions:
      • leave receiver gain identical to that used in Pulse Ideality Test
      • set pulse width to zero (no excitation)
      • acquire four single transient experiments separated by repetition time
      • apply no line broadening during fourier transform

      Specification: No peaks with a measured peak height of greater than 2X the noise level
      Actual: Pass

    8. Phase Stability (13 degree) Test
      Conditions:
      • place transmitter 37.0 Hz off-resonance from the H2O resonance
      • use two 90 degree 1H pulses (at a power level giving a 10 us 90 degree pulse) of equal phase separated by 1 ms (13 degrees)
      • acquire 32 single transient experiments separated by a sufficient relaxation time to ensure accurate amplitude measurement
      • phase first transient as pure adsorptive, apply identical phasing to all other transients
      • repeat test with 90 degree gaussian pulse using maximum power

      Specification: Standard deviation of the amplitude will be less than 0.71% which corresponds to a phase error of less than 0.1 degree when performed on 1H using rectangular and gaussian pulses.
      Actual: 0.30% (hard) and 0.36% (gaussian)

    9. RF Amplitude Predictability Test
      Conditions:
      • start with normal 90° rectangular pulse power single transient experiments, no dummy scans
      • increase pulse length by factor of 2 while concurrently reducing pulse power by 6 dB; repeat single transient experiment
      • continue increasing pulse length by 2 with 6 dB lower power over a greater than 40 dB total power change range
      • first experiment phased pure adsorptive; identical phase applied to rest
      • repeat test with 90 degree gaussian pulse using maximum power

      Specification: less than 10% peak height variation over complete range of powers
      Actual: 0.46% (hard) and 1.0% (gaussian)

    10. RF Excitation Predictability Test
      Conditions:
      • use maximum uncompressed power for pulse shaping
      • collect single transient rectangular 90 degree experiment at this power level separated by repetition time
      • follow with single transient gaussian experiment with the gaussian pulse width set 2.4 times the rectangular pulse width, same power
      • follow with single transient eburp-l experiment with the eburb-1 pulse width set 16.0 times the rectangular pulse width, same power no dummy scans
      • first experiment phased pure adsorptive; identical phase for rest

      Specification: The peak height variation shall be less than +/- 2%
      Actual: 0.5%

    11. Shaped RF Amplitude Stability Test
      Conditions:
      • single transient experiments will be performed changing waveform linear power control over 20 steps covering a minimum of 60 dB.
      • The amplitude of the resulting signal is measured
      • The pulse flip angle shall be a < 10° 1H pulse to ensure a linear response.

      Specification: The standard deviation of the linear fitting shall be less than 0.1%.
      Actual: 0.087%

    12. Gradient Recovery Stability Test
      Conditions:
      • setup as in pulse stability test except apply a 0.5 ms 30 G/cm rectangular gradient pulse followed by a 200 us delay prior to read pulse
      • repeat for -30 G/cm gradient pulse

      Specification: The standard deviation of amplitude shall be less than 0.15%.
      Actual: 0.10% (+30G) 0.03 (-30G)

    13. Gradient Echo Test
      Conditions:
      • setup as in 30 degree pulse stability test except apply a 100 us 10 G/cm gradient followed immediately by a 100 us -10 G/cm gradient and then a 100 us delay before single scan acquisition
      • acquire 100 experiments

      Specification: Standard deviation of amplitudes will be less than 0.2%.
      Actual: 0.07%

    14. Gradient Effect on Cancellation Test
      Conditions:
      • setup and run as in cancellation test except
      • apply a 1 ms 30 G/cm gradient followed by a 100 us delay prior to acquisition

      Specification: average total height (positive plus negative deviation) of each set of cancellation experiments (two phase cycle and four phase cycle) less than 2% of single transient peak height
      Actual: less than 2%

    15. Gradient Cancellation Test
      Conditions:
      • Sample: 1% H2O/99% D2O, sw=2000 Hz, at=4s, lb=1, nt=1
      • Pulse sequence: 1H 90 - 30 gauss/cm, 0.2 ms gradient pulse - 0.4ms delay - 1H observe.

      Specification: The residual signal shall be less than 0.1 % of the signal obtained without the gradient pulse applied
      Actual: less than 0.1%

    16. Gradient Recovery Test
      Conditions:
      • Using the 99% D2O sample, a WURST shaped gradient pulse of duration 2 ms is applied at 30 G/cm followed by a variable delay and a pulse.

      Specification: The complete recovery of both phase and amplitude of the resulting signal must be complete in no more than 1.3 ms.
      Actual: less than 1.3 ms

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  3. Shim Systems and VT Unit
    1. VT System Vibrations
      The high resolution single shot spectrum will be collected once with the VT gas and full VT equipment connected and once with the cooling system disconnected. Addition or modification of sidebands is monitored between the two spectra

    2. RT Shims Total Power
      Spec: The temperature of the probe equilibrated with no VT air flow will not exceed 30 degrees celcius.
      Actual: 17 degrees celcius

    3. RT B0 coil purity
      Test protocol: The CHCl3 line shape shall not degrade by more than the stated specification when spectra are acquired with the B0 field changed by a value corresponding to a drift rate per hour times 336 hours in the proton spectrum. No adjustment of shims or phase is allowed.
      Spec: less than 0.4/1.0/2.0 Hz change measured at 50/0.55/0.11% respectively
      Actual: Change = 0.15/0.37/1.26 Hz at 840 Hz shift (2.5 Hz/hr x 14 days)

    4. System Stability
      The spectrometer's homogeneity stability will be demonstrated using the 1% CHCl3 lineshape sample. The lineshape measurement will be recorded over 12 hours.
      Spec: Lineshape degradation of no more than 0.5/1.5/3 Hz (at 50%/0.55%/0.11% of the signal height) over a period of 12 hours.
      Actual: Change = 0.05/-0.01/-0.34 Hz

    5. VT Temperature Stability
      Spec: The measured frequency of the DSS in D2O shall not drift by more than +/- 0.9 Hz (+/- 0.1 degrees celcius) at a sample temperature setting of 15 degrees celcius for a period of 12 hours (sampling at 10 min. intervals). The test will span 12 hours between 6 pm and 6 am to minimize external effects.
      Spec: The linewidth at the 0.55% level of the DSS sample will not broaden by more than 10% or up to 9 Hz width at the 0.55% level, whichever is less, of the measured linewidth in the first spectrum. The test will span 12 hours between 6 pm and 6 am to minimize external effects.
      Actual: Maximum Frequency Change = -0.305 Hz
      Actual: Maximum Linewidth Change = 4.2%

    6. Temperature Gradient in Sample
      Spec: For a sample of 20 mM sodium acetate in D2O we will be able to obtain similar lineshape specifications on the acetate signal and the HOD signal (both < 0.5 Hz spinning) at 25 degrees celcius.
      Actual: HOD Res. = 0.36, OAc Res = 0.38

      Spec: The temperature of the sample will then be raised to 40 degrees celcius and again shimmed on the lock. With a linewidth of the HOD of < 0.5 Hz (linewidth at half height) linewidth of the acetate peak will be < 1.5 Hz. Standard VT flow rate of 15 lpm shall be used.
      Actual: HOD Res. = 0.40, OAc Res = 1.04

      Spec:The temperature of the sample will then be lowered to 5 degrees celcius and again shimmed on the lock. With a linewidth of the HOD of < 0.5 Hz (linewidth at half height) linewidth of the acetate peak will be < 1.5 Hz. Standard VT flow rate of 15 lpm shall be used.
      Actual: HOD Res. = 0.48, OAc Res = 0.68

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  4. RF Amplifiers
    1. Amplifier Droop
      Protocol: Amplifier droop will be measured over 20 ms with a 5% duty cycle. The droop will be measured at power levels corresponding to saturation (1 dB compression point) and 10 dB below saturation. Droop will be the comparison of the first 10% absolute integrated time domain signal with the last 10%. Droop will be measured using a digital storage oscilloscope, with the power attenuated through a matched 50 ohm load in place of a probe but the rest of the configurations standard.
      Spec: less than 8% droop for each amplifier
      Actual:

    2. Amplifier Rise and Fall Time
      Protocol: Amplifier rise and fall time measurements will be measured at the maximum rated pulse power, using a 2 msec pulse width, measured at the output of the amplifier.
      Spec: less than 200 ns
      Actual:

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  5. RF Stability
    1. X-Nucleus Amplitude Stability at Full Power
      Protocol: The standard pulse sequence for indirectly measuring heteronuclear pulse lengths (Figure 3.33a of Protein NMR Spectroscopy: Principles and Practice) is applied to a 13C-labeled sample, using a 90° 1H pulse and a 60° 13C pulse at a full rated power and a single transient is recorded. The amplitude of the resulting signal is measured after processing using matched line broadening. This experiment is repeated 30 times, with a sufficient time between experiments to ensure complete relaxation. The standard deviation (S.D.) of the signal amplitude is compared to the mean peak amplitude + the S.D. of the signal amplitude obtained with no 13C pulse applied (as determined from 30 control experiments).
      Spec: less than 1%
      Actual:

    2. X-Nucleus Amplitude Stability in Linear Range
      Protocol: The standard pulse sequence for indirectly measuring heteronuclear pulse lengths (Figure 3.33a of Protein NMR Spectroscopy: Principles and Practice) is applied to a 13C-labeled sample, using a 90° 1H pulse and a 13C RF field strength of 1 kHz and a single transient is recorded. The amplitude of the resulting signal is measured after processing using matched line broadening. This experiment is repeated 30 times, with a sufficient time between experiments to ensure complete relaxation. The standard deviation (S.D.) of the signal amplitude is compared to the mean peak amplitude + the S.D. of the signal amplitude obtained with no 13C pulse applied (as determined from 30 control experiments).
      Spec: less than 1%
      Actual:

    3. X-Nucleus Amplitude Stability in Linear Range
      Protocol: Rf amplifiers must be capable of performing spin lock experiments for up to 200 ms for 1H (Gamma*B1 = 10 kHz) and up to 50 ms for 13C (Gamma*B1 = 7.5 kHz) with droop of < 5%.
      Spec: droop less than 5%
      Actual:

    4. Transmitter and Amplifier Stability
      Protocol: Amplitude stability of all pulses from all transmitters will be better than 0.5% during any 24-hour period. This measurement will be made with the amplitude at -6dB relative to the 3 dB compression point of that amplifier.
      Spec: S.D. less than 0.5%
      Actual:
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  6. Lock
    1. Lock Stability
      Protocol: Twenty Hahn echo spectra will be recorded using a single transient (Equation 3.124 of Protein NMR Spectroscopy: Principles and Practice) of the doped water sample, using a 500 ms duration between the 90 degree and 180 degree pulses of the Hahn echo sequence. The zero order phase correction for each spectrum will be measured and the maximum phase variation from the mean value must not exceed the specification (which corresponds to a lock stability of 0.01 Hz).
      Spec: Maximum phase deviation from the mean less than +/- 3.6 degrees
      Actual: Max. Dev. -2.278 degrees

    2. Heteronuclear Spin Echo Difference
      Protocol: A two scan difference experiment will be performed on the concentrated sucrose sample to test the suppression of the center-band signal of the anomeric proton resonance. The intensity of the suppressed 12C center-band after two scans will be compared to the height of the natural abundance sidebands for a consecutive series of 20 experiments. A sufficient delay will be left between scans to ensure complete relaxation of the center-band and satellites and no BIRD or other sequence element can precede the spin echo sequence. The sequence shell be preceded by sixteen dummy scans with similar delays. The test will be run at 25 C.
      Spec: The residual signal of center-band shall be below satellite intensity in 19 out of 20 experiments.
      Actual: 19/20

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  7. Receiver System
    1. Noise
      The noise figure for the non-cryogenic preamplifiers, including all cabling and components from the probe to the digitizer.
      Spec: less than 1.0 dB for proton preamp, less than 1.5 for broadband preamp
      Actual:

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  8. Gradient Hardware
    1. Gradient Echo
      Protocol: A gradient echo experiment is performed on the doped water sample, with a 10 G/cm, 2 ms gradient square pulse to de-focus the magnetization and a 20 G/cm, 1 ms gradient pulse to refocus the magnetization. A single transient is recorded. The amplitude of the resulting signal is measured after processing without any applied line broadening. The experiment will be repeated 30 times, with sufficient time between scans to ensure complete relaxation. The standard deviation of the signal amplitude will be compared of the mean amplitude and must be less than the specification. The mean shall be greater than the signal amplitude determined by a single 90° pulse, followed by a delay equal to the total post-pulse delay used in the gradient experiments, corrected for diffusion losses. The mean of the observed signal amplitude in the gradient experiment must be greater than the mean of the signal amplitude following a single 90 degree pulse adjusted for spin-spin relaxation. The experiment will be conducted separately for the x, y, and z gradients. Specifications may be adjusted for any effects of diffusion of the liquid sample.
      Spec: mean > control*exp(-0.004/T2), S.D. < 0.5%
      Actual:

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  9. Probe Specifications
    1. H1 Lineshape and Resolution
      Protocol: The lineshape spectra shall be collected with a 90 degree pulse and a single transient with a fully-relaxed sample.
      Spec: less than 0.75/6.0/12.0 Hz (50/0.55/0.11%), non-spinning
      Actual: 0.73/5.03/9.59 Hz

    2. Sensitivity (ethylbenzene)
      Spec: greater than 2100:1 S/N for 3 out of 5 consecutive spectra. Specification will be obtained on a standard 0.1% ethylbenzene sample in a thin-wall (0.42 cm I.D.) tube.
      Actual: 2116.94, 2040.32, 2221.65, 2115.2, 2132.45

    3. Sensitivity (Sucrose, low-salt)
      Protocol: Acquisition parameters of 1.365s acquisition time, sweep width of 13000Hz, 2 steady state scans, 2 s recycle delay, 8 transients, no window function applied upon data processing. S/N measured using 200 Hz noise.
      Spec: greater than 400:1 S/N for 3 out of 5 consecutive spectra
      Actual: 415.251, 415.516, 415.643, 410.412

    4. Sensitivity (Sucrose, high-salt)
      Protocol: Acquisition parameters of 1.365s acquisition time, sweep width of 13000Hz, 2 steady state scans, 2 s recycle delay, 8 transients, no window function applied upon data processing. S/N measured using 200 Hz noise.
      Spec: greater than 250:1 S/N for 3 out of 5 consecutive spectra
      Actual: 295.286, 302.514, 290.09, 296.09, 293.629

    5. Deuterium Sensitivity
      Protocol: Sensitivity of the D2O 2H resonance will be measured using noise levels measured over a 1000 Hz interval. The test will be carried out using a 9 degree pulse and S/N will be measured using 1 KHz noise.
      Spec: greater than 5000:1 S/N for 3 out of 5 consecutive spectra
      Actual: 4920.92, 5007.81, 5004.22, 4866.12, 5029.91

    6. 90 degree Pulse Widths (low-salt)
      Spec: less than 7 us for proton, less than 11 us for carbon, less than 32 us for nitrogen and less than 175 us for deuterium.
      Actual:

    7. 90 degree Pulse Widths (high-salt, 250 mM NaCl)
      Spec: less than 10 us for proton, less than 11 us for carbon, less than 32 us for nitrogen and less than 175 us for deuterium.
      Actual:

    8. RF Homogeneity
      Spec: 810/90 > 65% for proton, 720/0 greater than 70% for carbon, and 720/0 greater than 70% for nitrogen.
      Actual:

    9. Power Handling for CW
      Actual:
      • Proton: greater than 12.5 kHz RF field for 100ms (5% duty cycle)
      • Carbon: greater than 10 kHz RF field for 50ms (5% duty cycle)
      • Nitrogen: greater than 2.5 kHz RF field for 100ms (5% duty cycle)
      • Deuterium: greater than 0.5 kHz RF field for 50ms (5% duty cycle)

    10. Water Suppression
      Protocol: The line width of the residual water peak following pre-saturation (50 Hz RF power level) will be less than the Specification. The test is performed with the sample non-spinning, utilizing single pulse excitation and no gradients. Acquisition parameters of 1.365s acquisition time, sweep width of 13000Hz, 2 steady state scans, 2 s recycle delay, 8 transients, pre-saturation with 50 Hz RF power level, no window function applied upon data processing.
      Spec: less than 70 Hz at the 100% level of the anomeric proton, less than 120 Hz at the 50% level of the anomeric proton.
      Actual: 61.331 Hz at 100% and 78.134 at 50%

    11. Gradient Amplitude
      Protocol: The gradient amplifiers must be capable of supplying sufficient power to generate the specified gradient amplitudes for 1 ms square pulses.
      Spec: greater than 60 G/cm for Z, greater than 28 G/cm for X and Y.
      Actual:

    12. Gradient Recovery
      Protocol: Using a 1 ms square gradient pulse the recovery to greater than 95% amplitude shall occur in less than the specified time.
      Spec: greater than 95% of signal intensity within 100 us for Z, less than 200 us for X and Y
      Actual:

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This page was last updated on June 21, 2006