REPORT
VICTOREEN
N e w Victoreen M o d e l 7 2 7 Logarithmic Count Rate Meter built to O R N L
SPECIFICATION
Q1454B.
Logarithmic Count Rate Meter MONITORING
for GAMMA
SYSTEMS
RAY SPECTROMETRY
Based on the Cooke-Yarborough circuit and of latest ORNL design, the Victoreen Model 727 Logarithmic Count Rate Meter is a widerange, five-decade instrument for use with all types of radiation detectors. Incorporating a Schmidt trigger circuit for discrimination, the instrument covers, on a single scale, a range of from 10 to 1,000,000 counts per minute without mechanical switching as on linear type rate meters. If your problem involves gamma monitoring with scintillation counter . . . beta-gamma monitoring with Geiger counter . . . gamma ray spectrometry—it will pay you to check these specifications: Range: From 10 cpm to 1 , 0 0 0 , 0 0 0 cpm in 5 decades Accuracy:
d z 2 % over entire r a n g e . Better than 1 % in vicinity of calibration point
Input Sensitivity:
=fc5 volt p e a k to peak minimum
Recorder Output: 0-10 millivolt C a l i b r a t i o n Check: Internal calibration source—six frequencies a v a i l a b l e : 3 6 0 , 7 2 0 , 1 4 4 0 , 3 6 0 0 , 7 2 0 0 and 14,400 cpm Pulse Height Discriminator: V a r i a b l e from - 5 0 to + 1 0 0 volts Drift: Less than 1 % in 2 4 hours Power Requirements: 115 volts, 6 0 cycles, 135 watts D i m e n s i o n s : Relay Rack Panel 83A"
χ 19"
Shipping Weight: 60 pounds
ΛΛ-7912
The Victoreen Instrument 5802-9 Hough Avenue
·
Company
Cleveland 3, Ohio
W O R L D ' S FIRST NUCLEAR C O M P A N Y For further information, circle number 22 A on Readers' Service Card, page 101 A 22 A
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ANALYTICAL CHEMISTRY
which are plotted against altitude, with miles on the right and kilometers on the left. These parameters to 200 km. were measured with pressure gages flown in Aerobee-Hi rockets. The nov elty of this particular experiment lies not only in the instrumentation, but in the method of its use. Mechanical and Ionization Gages. Two types of instruments are flown: mechanical pressure gages, some of which have a sensitivity to pressure changes of less than 10~5 mm. of mer cury, and ordinary Philips ionization gages to read absolute pressures from 10~4 to 10~e mm. of mercury and pres sure changes of 10~8 mm. of mercury. The mechanical gages gather data from 20 to 150 km., while the Philips gages perform best at altitudes above 100 km. Whereas these gages are cali brated before flight to measure only one parameter (pressure), the proper placement of gages on the side of the rocket enables a determination of the density and temperature vs. altitude as well as that of the pressure. During powered flight the rocket is intentionally spun about its long axis. Because most rockets precess in free flight so that the long axis rarely lies along the trajectory, the side mounted gages will enounter pressures which are dependent on the instantaneous atti tude of the rocket. In particular, the measured pressure is spin-modulated, and above 100 km., the atmospheric density is a simple function of the rocket attitude, rocket velocity, the pressure gage temperature, and the peak-to-peak value of the spin pres sure modulation. Density (P) = j-^ (attitude, velocity, Τ gage, AP) The absolute pressure Ρ = f2 (attitude, Tgage, velocity, Τ ambient) where Γ ambient is equal to the ambient atmospheric tempera ture. The gas law relation is P = p(k/m)
(Tambient)
where k is Boltzmann's constant and m is the average mass of the gas particles (measured by other rocket experi ments) . In the above equations, gage pres sure changes and gage temperatures are directly measured quantities. Radar plots the rocket velocity and altitude; magnetic and optical aspect devices measure the rocket attitude at all times. The three equations with the three unknowns are sufficient to de duce temperature and density from pressure measurements. The mean free path numbers are computed di rectly from the density and pressure figures.
