Single Scattering of Fast Electrons

Bleuler, E.; Scherrer, P.; Zünti, W.

doi:10.1103/physrev.61.95.2

Cited by 10 publications

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“…Consequently the absorptioil and scattering of /3 radiation have only been described a ians. empirically, principally with counting geometries of less than 29 ster d ' T h e absorption process, of interest both as a source of error in disintegrationrate measurements and as an energy determination method, has been the subject of a volumii~ous literature (6,17,19,20,21,27,29,41,42). Our knowledge manuscript received J u l y 11, 1965. of the back-scattering of 0 radiation is largely due t o experimental work performed in coililection with disintegration-rate determinations using < < 2~ geometry systems (12,IG,22,26,50,51).…”

Section: Introductionmentioning

confidence: 99%

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DISINTEGRATION-RATE DETERMINATION BY 4π-Counting: PART III. ABSORPTION AND SCATTERING OF Β RADIATION

Pate¹,

Yaffe²

1955

Can. J. Chem.

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PART 111. ABSORPTION AND SCATTERING OF B RADIATION1 T h e "coincident discharges" irl a 4x-counter have been esamined and found t o be due in t h e main t o gas and wall back-scattering. This can be resolved into two components-scattering near t o and I N T R O D U C T I O NPrevious publications in this series (37, 38, 39) have described experimental work aimed a t improving the accuracy of absolute counting using a 49-counter. In this paper additional experimental data are presented, which enable identification t o be made of the agency giving rise t o the discharges occurring coiilcidently in both half-counters, and exami~lation t o be effected of some of the scattering and absorption processes involved in using a 49 steradian geometrical arrangement.The penetration of electronic radiation through matter is a complex phenomenon owing t o the variety of processes by which interaction may occur ( 5 ) .With an initially collimated beam of moiloenergetic electrons, interaction with a layer of material up t o a superficial density of a few hundred pgm./cm.2 occurs by means of a few scattering events per electron. This results in the beam spreading without too great an energy or intensity loss. With thicker layers, Inore scattering events per electron occur and a transition t o "multiple scattering" takes place. With still thiclier layers the electroils no longer have a preferred direction of motion and the process resembles diffusion. The number of electrons now emerging from the foil decreases with increasing foil thickness, i.e. absorptioil of the radiation occurs.The single scattering of electrons has been treated theoretically (2, 33) and the multiple scattering has beell treated in an approximate way (4).When the system is further complicated by an uncollimated /3 radiation with a coi~tinuous energy spectrum, a theoretical analysis is very difficult. Consequently the absorptioil and scattering of /3 radiation have only been described a ians. empirically, principally with counting geometries of less than 29 ster d'T h e absorption process, of interest both as a source of error in disintegrationrate measurements and as an energy determination method, has been the subject of a volumii~ous literature (6,17,19,20,21,27,29,41,42 For personal use only.

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Section: Introductionmentioning

confidence: 99%

“…T h e absorption process, of interest both as a source of error in disintegrationrate measurements and as an energy determination method, has been the subject of a volumii~ous literature (6,17,19,20,21,27,29,41,42 For personal use only.…”

Section: Introductionmentioning

confidence: 99%

DISINTEGRATION-RATE DETERMINATION BY 4π-Counting: PART III. ABSORPTION AND SCATTERING OF Β RADIATION

Pate¹,

Yaffe²

1955

Can. J. Chem.

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“…Consider the situation, for simplicity, of a substance like Au'" whose spectrum has been worked out. This substance has one beta-ray and (27) (8), (9), (1o) (12) Here F(x) is a function denoting the absorption of the electrons as a function of the thickness.…”

Section: Measurement Of Internal Conversion Electronsmentioning

confidence: 99%

The Use of Coincidence Counting Methods in Determining Nuclear Disintegration Schemes

Mitchell

1948

Rev. Mod. Phys.

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I. INTRODUCTIOÑOR some years the author and his collaborators'* have been using coincidence counting techniques as an aid in the determination of nuclear disintegration schemes. The information obtained by this method, when taken together with that obtained with the help of a magnetic analyzermagnetic lens or 180' type magnetic spectrographis at present one of the best methods of obtaining nuclear disintegration schemes, or the energy levels of radioactive nuclei. A comparison of the two methods gives a picture of the advantages and disadvantages of each.Any magnetic analyzer, to be sure, has much greater resolving power than does the coincidence method. In principle, a resolution (AHp/Hp) in momentum of the electrons measured of i -2 percent can be obtained. Measurement of gamma-ray energies can be obtained to an accuracy of 1 to 5 percent by measuring the energy of photoelectrons produced in some radiator, such as lead. It is not difhcult to measure the energies of the electrons ejected from the Z and I. shell by some gamma-ray and thereby obtain the energy of the gamma-ray. In addition, one can measure the momentum distribution of Compton electrons produced in an element of Iow atomic number, say copper or aluminum, by the gamma-rays under investigation. This method can serve as a check on gamma-ray energies obtained by the photo-effect and is particularly useful in the two cases: (I) when the energy of the gamma-ray is so high that the probability of production of photoelectrons becomes small; and, (2) when two gamma-rays are so situated that the Iline of one is superimposed on the X line of the other, for some particular radiator.The energy of gamma-rays can be measured with considerable accuracy by this method, *References are to be found in the bibliography at the end of this article. provided sources of high activity are available.The problem is to determine the energy level scheme from this information which is, at the same time, consistent with the spectrum of the disintegration electrons.The determination of the momentum distribution of the disintegration electrons (beta-ray spectra) poses a somewhat different problem. The thickness of the source and the material upon which it is mounted influence the shape of the distribution especially at the low energy end of the spectrum. One is therefore forced to use sources of very high specihc activity in order to obtain the best results. When the distribution is measured, a "Fermi Plot" is made of the results, and a decision made as to whether the spectrum is simple or complex. If the spectrum consists of two groups, a determination of the two end points can be made with fair accuracy.If more than two groups are present, the accuracy of determining the end points of the lower energy groups is considerably less.With the help of the information from the gamma-ray spectra and that of the beta-ray analysis, including the occurrence of internal conversion lines, one attempts to draw up a self-consistent energy level diagram. This method does not allow one to be cer...

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“…The theoretical distribution N(e) can be written as constant Xe 2 (€ 0 -€) 2 0(Z, e), where 0 gives the Coulomb field effect. 6 In counter / the 17.4-kev calibration line was found to have a Gaussian shape of standard deviation a = 700 ev, over a range of at least do3a. In counter 77 <r was 1100 ev.…”

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confidence: 91%

Theβ-Spectrum ofH3

Hanna¹,

Pontecorvo²

1949

Phys. Rev.

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T HE 130-inch cyclotron has accelerated protons out to a radius of 58i" (approximately the « = 0.2 point) or to an estimated energy of 240 Mev since the first of the year. Measurement of the C" activity of a carbon-tipped probe indicates average currents of about 0.1 jua at this radius and radio-autographs of the target show the beam to be about 1" in height and well centered vertically on the probe. Eastman Kodak NTB plates placed along the probe show, among many proton recoil tracks, w~ and ir + tracks.About 15 kw of r-f power for the Dee is furnished by a grounded grid oscillator with feedback through the Dee. The natural frequency of the Dee is varied from 26 to 18 megacycles by a rotating condenser. The condenser which is in the Dee tank consists principally of a rotor of copper-plated, thin-toothed zircon disks mounted on a shaft parallel to the back edge of the Dee and a Dee stator which is on the back edge of the Dee. The magnetic drag of this rotor up to 2000 r.p.m. is small compared to the power taken by the rotor shaft seals. The copper-plated ceramic disks already give promise of satisfactory life.Ion loading of the Dee is obviated by a negatively biased grid structure covering the linear above and below the Dee. Globar resistors break the grid into lengths too short to resonate to the Dee frequencies.

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Single Scattering of Fast Electrons

Cited by 10 publications

References 1 publication

DISINTEGRATION-RATE DETERMINATION BY 4π-Counting: PART III. ABSORPTION AND SCATTERING OF Β RADIATION

DISINTEGRATION-RATE DETERMINATION BY 4π-Counting: PART III. ABSORPTION AND SCATTERING OF Β RADIATION

The Use of Coincidence Counting Methods in Determining Nuclear Disintegration Schemes

Theβ-Spectrum ofH3

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