摘要:

Two liquid scintillation type neutron detectors with efficiencies of the order of 5% for counting 130‐Mev neutrons have been studied. A fairly monoenergetic source of neutrons was obtained from the photodisintegration of deuterons. Estimates were made of the efficiencies of the counters as a function of bias. Experiments indicate: (1) an appreciable effect of the products of neutron reactions with carbon; (2) the efficiency can be more accurately predicted for a small counter although the behavior of large counters can be qualitatively predicted; (3) the attenuation due to a lead shield in the beam depends upon the neutron energy, the bias, and the geometry; (4) lead shielding on the sides is relatively unimportant if kept thin.

ISSN:0034-6748    

DOI:10.1063/1.1715492

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

This paper reports a self‐contained tritium gas target including beam collimator, target cell, and gas reservoir which has been used for the production of neutrons from the T(d,n)He4and T(p,n)He3reactions. Beam collimators are 0.14‐in. tantalum apertures aligned in precision 1‐in. tubing to assure accurate beam measurement. The gas cell is516in. diam and may be any length less than 3 in. The target window is a 0.00005‐in. nickel foil soldered on a ¼‐in. i.d. re‐entrant tube. Tritium is supplied from a uranium‐tritide oven; hydrogen‐tritium exchange is minimized by the use of nonhydrogenous materials. A discussion is given of handling of tritium. The target will tolerate a 1 &mgr;amp beam of 2‐Mev deuterons for several days without foil damage.

ISSN:0034-6748    

DOI:10.1063/1.1715493

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A simple, sensitive, electrical pressure measurement device has been constructed which is capable of measuring and recording absolute or differential pressures of corrosive materials of isolated systems. A linear variable differential transformer attached to a sylphon bellows indicates differential pressure across the bellows or serves as a null indicator when an unknown pressure on one side of the bellows is balanced with a gas of measurable pressure on the other side. In order to prevent inelastic deformation, the motion of the of the bellows is limited to 60 mm Hg, although larger pressure differentials can be measured. The sensitivity is independent of temperature and pressure and the device can be compensated for temperature. Absolute pressures and small differential pressures can be measured to ±0.02 mm Hg with an input signal of 2 kc, and to ±0.005 mm Hg with an input signal of 10 kc. A vacuum tube voltmeter with a full scale of 1 millivolt is used as the output indicator.

ISSN:0034-6748    

DOI:10.1063/1.1715494

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A temperature controller using small bead thermistors as temperature sensing elements has been developed. The controller has an over‐all range of +20 to +300°C, or −60 to +190°C, using 51A2 or 32A12 thermistors, respectively, in an ac bridge. Extension of the operating temperature range to other limits is possible using other sensing elements. Linear proportional action is achieved with power relay output by comparing the amplified and rectified bridge signal with a stable and linear sawtooth wave form. This comparison controls the fractional ``on'' time of the power relay during a periodic ``on‐off'' cycle. The controller offers stable control under all conditions of unbalance, and is stable to 0.1°C or better over an eight‐day period.

ISSN:0034-6748    

DOI:10.1063/1.1715495

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A system used to obtain power spectra for the frequency range from 0.00006 to 0.02 cps is described. The instruments shifts the low frequencies into the audio range where they are analyzed with an electronic audio‐frequency wave analyzer. The frequency shift is achieved by recording the low‐frequency phenomenon on photographic film in the form of a variable‐area recording. The film is played back at a greatly increased rate, modulating a phototube current which is fed into an analyzer. Speed‐up ratios, i.e., multiplications in frequency, of more than 500 000 times have been attained.

ISSN:0034-6748    

DOI:10.1063/1.1715496

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The attenuation of different types of light guides used with scintillation counters has been measured. The detrimental effect of the guides in scintillation spectrometry has been studied.

ISSN:0034-6748    

DOI:10.1063/1.1715497

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The design of a double‐crystal spectrometer attachment to the Norelco wide‐range goniometer is described. The outstanding features of this design are: (1) the axes of rotation of both crystals are made parallel in the construction of the instrument; (2) one can easily align the instrument in the parallel (n, ‐n) or antiparallel (n, +n) setting in less than one hour; and (3) no modification of the Norelco equipment is needed, and good use is made of the wide‐range goniometer for setting the first crystal at the proper Bragg angle for reflection. Typical parallel position rocking curves for single‐crystal germanium and silicon are presented.

ISSN:0034-6748    

DOI:10.1063/1.1715498

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A swinging‐gate type valve with associated triggering mechanism is employed as a protective device for quickly stopping a sudden accidental inrush of air to a vacuum system. The electrical triggering mechanism uses no vacuum tubes. For a large inrush of air, the valve will close in less than 0.01 sec.

ISSN:0034-6748    

DOI:10.1063/1.1715499

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A E1T decade‐counter tube is used in conjunction with an energy‐storage counting circuit. The stray capacitance at the anode of the decade tube serves as the energy storage element, while the stabilizing characteristic of the tube itself makes the circuit completely aperiodic. A secondary‐emission tube, type EFP60, produces a 0.15‐&mgr;sec high current pulse for resetting the decade counter to zero at each tenth input pulse. Double‐pulse resolution of <1 &mgr;sec and a continuous rate of above 106pps have been achieved.

ISSN:0034-6748    

DOI:10.1063/1.1715500

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A method is described for measuring the spectrum of fast neutrons with a series of foil detectors. The detectors consist of Au and Au plus Cd for determining the thermal flux, Pu239shielded with B10for determining the total fast flux, Np237for determining the total flux above 0.75 Mev, U238for determining the total flux above 1.5 Mev, and S32for determining the total flux above 2.5 Mev. From these data the spectrum of fast neutrons can be constructed reasonably well for spectra similar to that of fission. The amount of induced activity in the detecting elements is determined with scintillation counters, which are calibrated by irradiation of suitable foils with thermal neutrons.Fast neutron tissue dose can be calculated from the measured spectrum. Since the foil method of measuring spectra works well for high intensity bursts of neutrons, dosimetry may be accomplished under conditions where other methods, e.g., the ionization chamber and proportional counter, would lead to questionable data.

ISSN:0034-6748    

DOI:10.1063/1.1715501

出版商:AIP    

年代:1956

数据来源: AIP