CIA STARGATE release
CIA-RDP96-00788R001500190001-6
Warning: text for all documents has not been verified. Errors are possible. Check the original by document ID on CREST.
13 pages, machine transcribed from the CIA’s released scan.
Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 TAB .. 1 . Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
SG1B Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 £ Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 .. TAB 1 - Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
SG1B Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 Next 1 Page(s) In Document Exempt Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 TAB - - ... Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
SG1B Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 Next 4 Page(s) In Document Exempt Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 TAB 1 - Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
SG1B Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 Next 5 Page(s) In Document Exempt Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
662 Optoelectronic Devices 0.5 EFFECTIVE QUANTUM EFFICIENCY 0.4 sin 0.3 - X 0.0 0.4 0.6 : 0.8 1 1.2 1.4 1.6 WAVELENGTH (MICRONS) . 73 Fig. 24 Effective quantum efficiency (hole-electron pairs/photon) versus wavelength for Ge and Si photodetectors. (After Melchior and Lynch, Ref. 39.) R 0 Ipp[ w] C (a) 1 -2 -0 -2 A R C 1 Fig. 25 (a) Equivalent circuit and (b) noise equivalent circuit of a photodiode, where R is the series resistance and C is the junction capacitance. (After DiDomenico and Svelto, Ref. 35.) CPYRGHT 4 Photodetectors available power for the photo 118 It is interesting to compare E For a typical photodiode with a photoconductor with the sar available power from the phot from the photoconductor. The signal-to-noise perform equivalent noise circuit shown noise source due to the series source. The signal-to-noise ra! Comparing Eq. (44) with Eq. at high-level detection where SNR is comparable; at low-lev however, the SNR of the pho B. The p-i-n Photodiode depletion-layer photodetector. (the intrinsic layer) can be tai frequency response. A typical Fig. 26(a). Absorption of ligh pairs. Pairs produced in the de will eventually be separated by external circuit as carriers drif Under steady-state condition biased depletion layer is given where Jar is the drift current region and Jairr is the diffusior side the depletion layer in the t reverse-biased junction. We : assumptions that the thermal g surface n layer is much thinn electron generation rate is give Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 ... : 0.2 ơ 4 He-Ne RUBY He-Ne GaAs YA G He-Ne ARGON 1 I 1 * VISIBLE SPECTRUM 1
Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 DETECTORS AND DETECTOR SYSTEMS CPYRGHT SILICON CHARGED-PARTICLE DETECTORS characteristics. The detector changes include in- creased noise and changes in voltage drop across the load resistor, which require adjustments to the applied bias voltage, which in turn change the electric-field strength. Thus carrier trapping and increased detector noise are degrading to energy resolution. . Resolution degradation appears as a broadening of the response for a monoenergetic source. With increasing doses of neutrons, charged particles, or fission frag- ments, the low-energy side of the response peak may begin to show a definite secondary peak. Continued irradiation results in further broadening, until, in ex- treme cases, the multiple peaks may merge com- pletely. Electron bombardment tends to increase leak- age current, resulting in excess detector noise, which broadens response peaks. Some of these damage ef- fects may undergo a degree of annealing, but there is always a significant residual deterioration after a suffi- cient dose has been accumulated. Partially depleted detectors are more susceptible than are fully depleted devices to deterioration from radia- tion damage. Radiation damage for different types of detectors are compared in Table 2, which gives the dose for various particles to significantly deteriorate the detectors. OPERATING TEMPERATURE As a rule of thumb, increasing the operating tempera- ture of a charged-particle detector causes the leakage current to increase by a factor of 3 for each 10℃ rise, resulting in a noise-width increase of approximately 1.7 keV per 10°Crise. The upper temperature limit is deter- mined by the maximum acceptable noise or by the ultimate breakdown of the detector (usually between 45 and 55°℃). The effects of high-temperature break- down are permanent and are not covered by the war- ranty terms. An additional effect is the shift in detector bias caused by the higher leakage current. This leak- age current increases the voltage drop across the se- ries bias resistor, thus lowering the bias voltage across the detector. When high-temperature operation is necessary, a constant sensitive depth is maintained over the entire operating temperature range only if a totally depleted detector is used with sufficient overbias to compensate for the drop across the series bias resistor, which should be as small as possible (usually 1 to 3 MS2 is adequate). Decreasing the operating temperature of the detector reduces junction noise and leakage current. However, the capacitance of the device is a constant limiting parameter of the system noise. Another limitation to successful operation at low temperatures is the expan- sion coefficient of the detector's component parts. The expansion coefficient is similar for silicon and for lavite, the ring in which the silicon wafer is mounted, but is quite different for the bonding epoxy. Therefore at very low temperatures the epoxy may crack, causing exces- sive noise or loss of contact. The probability of low- temperature damage increases with detector size. For cooled operation, detectors fabricated with cryogenic epoxy may be special ordered from ORTEC. Another effect of decreasing the operating tempera- ture of a silicon detector is an increase of the average energy necessary to create an electron-hole pair, E. Due to a widening of the bandgap of silicon in the temperature range from 300 K to 80 K, E increases from 3.62 eV to 3.72 eV. A result of this increase is an apparent shift in energy of a measured spectroscopic line. For instance, Fig. 8 shows the apparent peak shift of the 5.477-MeV 241Am alpha particle peak in the 4.2- K to 320-K temperature range measured with silicon charged-particle detectors. SHOCK AND VIBRATION Many ORTEC surface-barrier detectors have been subjected to the shock and vibration tests required for Table 2. Comparison of Radiation Damage in Silicon and Germanium Particle Detectors Radiation Damage (particles/cm2) Type of Detector Electrons Fast Neutrons Protons Alpha Particles Fission Fragments Surface barrier 1013 1012 1010 10º 108 Diffusion junction 1013 1012 1010 109 108 Si(Li) 1012 1011 108-10º Ge(Li) 108-109 #1 Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 27
SG1B Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6 Approved For Release 2000/08/08 : CIA-RDP96-00788R001500190001-6
Appr wed FerREY 3 Chap. 39 a K-S d S E Fig. 39,-17 ing "arged. (a) Show that the lif_al volume. (b) Show that ated by integrating the Poynting e equal to the rate at which the energy density for all points within he Poynting vector point of view, zh the wires but through the space we must first find B, which is the =ing the charging process; see Fig. CPYRGHT Nature and Propagation of Light CHAPTER 40 40-1 Light and the Electromagnetic Spectrum Light was shown by Maxwell to be a component of the electromagnetic spectrum of Fig. 40-1. All these waves are electromagnetic in nature and have the same speed c in free space. They differ in wavelength (and thus in frequency) only, which means that the sources that give rise to them and the instruments used to make measurements with them are rather different .* The electromagnetic spectrum has no definite upper or lower limit. The labeled regions in Fig. 40-1 represent frequency intervals within which a common body of experimental technique, such as common sources and com- mon detectors, exists. All such regions overlap. For example, we can pro- duce radiation of wavelength 10-3 meter either by microwave techniques (microwave oscillators) or by infrared techniques (incandescent sources). Frequency, cycles/sec 10ª 104 10° 10ª 1010 102 1014 1016 10 18 1020 1022 Visible Power -... Infrared Ultraviolet Gamma rays Radio 10° 104 10$ 1 10-3 10-4 10-8 10-8 10-10 10-12 10-44 Wavelength, meters Fig. 40-1 The electromagnetic spectrum. Note that the wavelength and frequency scales are logarithmic. * For a report of electromagnetic waves with wavelengths as long as 1.9 X 107 miles the student should consult an article by James Heirtzler in the Scientific American for March 1962. 993 x-rays Microwaves
Approved For Release 2000/08/98 ~ CIA REPO6,007898044 2004 Chap. 4( 994 NATURE AND PROPAGATION OF LIGHT wolet yellow orange md 100 8 80 Relative sensitivity 60 -40 20 0 400 450 500 550 600 650 700 Wavelength, mu · Fig. 40-2 The relative eye sensitivity of an assumed standard observer at different wave- lengths for normal levels of illumination. The shaded areas represent the (continuously graded) color sensations for normal vision. "Light" is defined here as radiation that can affect the eye. Figure 40-2, which shows the relative eye sensitivity of an assumed standard observer to radiations of various wavelengths, shows that the center of the visible region is about 5.55 X 10-7 meter. Light of this wavelength produces the sensa- tion of yellow-green .* In optics we often use the micron (abbr. u) the millimicron (abbr. mu), and the Angstrom (abbr. A) as units of wavelength. They are defined from 1 = = 10-6 meter 1 mu = 10-9 meter 1 A = 10-10 meter. Thus the center of the visible region can be expressed as 0.555 u, 555 mu, or 5550 A. The limits of the visible spectrum are not well defined because the eye sensitivity curve approaches the axis asymptotically at both long and short wavelengths. If the limits are taken, arbitrarily, as the wavelengths at which the eye sensitivity has dropped to 1% of its maximum value, these limits are about 4300 A and 6900 A, less than a factor of two in wavelength. The eye can detect radiation beyond these limits if it is intense enough. In many experiments in physics one can use photographic plates or light-sensi- tive electronic detectors in place of the human eye. * See "Experiments in Color Vision" by Edwin H. Land, Scientific American, May 1959, and especially "Color and Perception: the Work of Edwin Land in the Light of Current Concepts" by M. H. Wilson and R. W. Brocklebank, Contemporary Physics, December 1961, for a fascinating discussion of the problems of perception and the distinc- tion between color as a characteristic of light and color as a perceived property of objects.