Abstract

A method of measuring refractive indices of gases in the vacuum ultraviolet using the electron beam from a 4.5-MeV microtron to produce Čerenkov radiation in the gases is described. In this method the threshold pressures for Čerenkov radiation in the ultraviolet and visible regions are compared for electrons of the same velocity. The ultraviolet detectors used in the present experiment are photomultipliers with gold photocathodes and windows of: (a) fused silica, and (b) “Spectrosil” to give results at about 1900 Å and a nitric oxide ionization chamber with a lithium fluoride window for results at about 1200 Å.

Preliminary results are quoted for the refractive indices of argon and nitrogen at the above wavelengths. The calculation of dispersion formulas has been deferred until further measurements have been made.

© 1963 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. T. Larsen, dissertation 1939, Zur Kenntnis der Refraktion und Dispersion von Edelgasen und edelgasäunlichen Hydriden und Deutriden (Gleerupska Universtät-Bokhandeln, Lund, Sweden).
  2. A. Dalgarno and A. E. Kingston, Proc. Roy. Soc. (London) A259, 424 (1960).
    [Crossref]
  3. J. Koch, Arkiv. Mat. 9, No. 6 (1913).
  4. P. G. Wilkinson, J. Opt. Soc. Am. 50, 1002 (1960).
    [Crossref]
  5. R. E. Jennings and P. I. P. Kalmus, Nucl. Instr. Methods 6, 209 (1960).
    [Crossref]
  6. D. K. Aitken, R. E. Jennings, A. S. L. Parsons, and R. N. F. Walker, Transition Radiation in Čerenkov Detectors (to be published).
  7. M. R. Bhiday, R. E. Jennings, and P. I. P. Kalmus, Proc. Phys. Soc. (London) 72, 973 (1958).
    [Crossref]
  8. See, for instance, J. V. Jelley, Čerenkov Radiation (Pergamon Press, Ltd., London, 1958).

1960 (3)

A. Dalgarno and A. E. Kingston, Proc. Roy. Soc. (London) A259, 424 (1960).
[Crossref]

R. E. Jennings and P. I. P. Kalmus, Nucl. Instr. Methods 6, 209 (1960).
[Crossref]

P. G. Wilkinson, J. Opt. Soc. Am. 50, 1002 (1960).
[Crossref]

1958 (1)

M. R. Bhiday, R. E. Jennings, and P. I. P. Kalmus, Proc. Phys. Soc. (London) 72, 973 (1958).
[Crossref]

1913 (1)

J. Koch, Arkiv. Mat. 9, No. 6 (1913).

Aitken, D. K.

D. K. Aitken, R. E. Jennings, A. S. L. Parsons, and R. N. F. Walker, Transition Radiation in Čerenkov Detectors (to be published).

Bhiday, M. R.

M. R. Bhiday, R. E. Jennings, and P. I. P. Kalmus, Proc. Phys. Soc. (London) 72, 973 (1958).
[Crossref]

Dalgarno, A.

A. Dalgarno and A. E. Kingston, Proc. Roy. Soc. (London) A259, 424 (1960).
[Crossref]

Jelley, J. V.

See, for instance, J. V. Jelley, Čerenkov Radiation (Pergamon Press, Ltd., London, 1958).

Jennings, R. E.

R. E. Jennings and P. I. P. Kalmus, Nucl. Instr. Methods 6, 209 (1960).
[Crossref]

M. R. Bhiday, R. E. Jennings, and P. I. P. Kalmus, Proc. Phys. Soc. (London) 72, 973 (1958).
[Crossref]

D. K. Aitken, R. E. Jennings, A. S. L. Parsons, and R. N. F. Walker, Transition Radiation in Čerenkov Detectors (to be published).

Kalmus, P. I. P.

R. E. Jennings and P. I. P. Kalmus, Nucl. Instr. Methods 6, 209 (1960).
[Crossref]

M. R. Bhiday, R. E. Jennings, and P. I. P. Kalmus, Proc. Phys. Soc. (London) 72, 973 (1958).
[Crossref]

Kingston, A. E.

A. Dalgarno and A. E. Kingston, Proc. Roy. Soc. (London) A259, 424 (1960).
[Crossref]

Koch, J.

J. Koch, Arkiv. Mat. 9, No. 6 (1913).

Larsen, T.

T. Larsen, dissertation 1939, Zur Kenntnis der Refraktion und Dispersion von Edelgasen und edelgasäunlichen Hydriden und Deutriden (Gleerupska Universtät-Bokhandeln, Lund, Sweden).

Parsons, A. S. L.

D. K. Aitken, R. E. Jennings, A. S. L. Parsons, and R. N. F. Walker, Transition Radiation in Čerenkov Detectors (to be published).

Walker, R. N. F.

D. K. Aitken, R. E. Jennings, A. S. L. Parsons, and R. N. F. Walker, Transition Radiation in Čerenkov Detectors (to be published).

Wilkinson, P. G.

Arkiv. Mat. (1)

J. Koch, Arkiv. Mat. 9, No. 6 (1913).

J. Opt. Soc. Am. (1)

Nucl. Instr. Methods (1)

R. E. Jennings and P. I. P. Kalmus, Nucl. Instr. Methods 6, 209 (1960).
[Crossref]

Proc. Phys. Soc. (London) (1)

M. R. Bhiday, R. E. Jennings, and P. I. P. Kalmus, Proc. Phys. Soc. (London) 72, 973 (1958).
[Crossref]

Proc. Roy. Soc. (London) (1)

A. Dalgarno and A. E. Kingston, Proc. Roy. Soc. (London) A259, 424 (1960).
[Crossref]

Other (3)

T. Larsen, dissertation 1939, Zur Kenntnis der Refraktion und Dispersion von Edelgasen und edelgasäunlichen Hydriden und Deutriden (Gleerupska Universtät-Bokhandeln, Lund, Sweden).

See, for instance, J. V. Jelley, Čerenkov Radiation (Pergamon Press, Ltd., London, 1958).

D. K. Aitken, R. E. Jennings, A. S. L. Parsons, and R. N. F. Walker, Transition Radiation in Čerenkov Detectors (to be published).

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (5)

Fig. 1
Fig. 1

Diagram of the Čerenkov detector.

Fig. 2
Fig. 2

A typical response of the visible-region photomultiplier to change of pressure in the Čerenkov chamber, in this case containing nitrogen. The dark current and x-ray background have been subtracted. The deviation from linearity at high pressures is due to the Čerenkov cone being cut off by the geometry of the system.

Fig. 3
Fig. 3

The detector responses used in calculating the effective wavelength taken from various published data: (a) the photomultiplier with a gold photocathode and fused silica window; (b) the same but with a Spectrosil window; (c) the nitric oxide chamber response including the effect of the lithium fluoride pressure window.

Fig. 4
Fig. 4

Diagram of the nitric oxide ionization chamber. The gas is at a pressure of 25 mm Hg. The outer casing is held at a positive voltage.

Fig. 5
Fig. 5

The response of the ionization chamber to pressure change of argon in the Čerenkov chamber. The signal below the Čerenkov threshold follows a p 1.60 law and extrapolation to pressures above threshold is justified by obtaining a similar background over the whole pressure range when the chamber is reversed and no Čerenkov radiation enters the detector. A p 1.44 law is obtained in the reversed case.

Tables (1)

Tables Icon

Table I Measurements of refractivities of argon and nitrogen using the Čerenkov radiation method. Detectors are (a) photomultiplier with gold photocathode and fused silica window; (b) photomultiplier with gold photocathode and “Spectrosil” window; (c) nitric oxide ionization chamber with a lithium fluoride window. Refractivities calculated from the dispersion formula of Wilkinson4 are given for nitrogen and from Larsen’s formula1 for argon. Errors are standard deviations.

Equations (15)

Equations on this page are rendered with MathJax. Learn more.

n λ 2 1 = N e 2 π m c 2 i λ 2 λ i 2 f i λ 2 λ i 2 ,
n 1 = 1.2048 × 10 6 ( 0.209646 0.87882 × 10 10 ν 2 + 0.209646 0.91001 × 10 10 ν 2 + 4.941724 2.69636 × 10 10 ν 2 ) ,
n 2 1 = 5.547 × 10 4 ( 1 + 5.15 × 10 5 λ 2 + 4.19 × 10 11 λ 4 + 4.09 × 10 17 λ 6 + 4.32 × 10 32 λ 8 + ) ,
β n ( τ uv λ uv ) = 1.
β n ( τ vis λ vis ) = 1 ,
n ( τ vis λ vis ) = n ( τ uv λ uv ) .
n ( τ vis λ vis ) 1 n ( τ uv λ vis ) 1 = the ratio of fringe counts , = F ( say ) .
( n ( τ uv λ uv ) 1 ) / ( n ( τ uv λ vis ) 1 ) = F .
d N d l A β n > 1 [ β n ( λ ) 1 ] d λ λ 2
β 1 β 2 g ( β ) d β = 1 ,
η = λ f ( λ ) d λ λ 2 ,
d R d l = A λ β β 2 [ β n ( λ ) 1 ] f ( λ ) λ 2 g ( β ) d λ d β ,
d R d l = A λ [ β n ( λ ) 1 ] f ( λ ) λ 2 d λ = η A [ β ¯ n ¯ ( λ ) 1 ] ,
η n ¯ ( λ ) = λ n ( λ ) f ( λ ) λ 2 d λ .
η r ¯ ( λ ) = λ r ( λ ) f ( λ ) λ 2 d λ .