1,4.
REFERENCES
339
istic green color produced by X—rays. A controlled leak of hydro—
gen
from a tank of this gas would be better than the system de—
scribed, but more complicated.
Unless the cathode C, gure 10—12, is water cooled, it will over…
heat and emit gases which not only lower the voltage but also
introduce undesirable ions in the bombarding beam, and the heat
may melt the wax holding the discharge tube to the cathode.
Premziom.
(1) The observation end must be the grounded
side of the high voltage system and must be kept grounded at all
times, as in gure 10—12. A small static spark, of no serious
danger, may be picked up
from the target tube even though it is
grounded; hence, touch this tube with your hand before looking
into the eyepiece.
(2) Keep away from the anode end of the tube at all times.
(3) Do not operate the apparatus
for too long a period of time
because of the x-rays produced at the anode.
(4) Be sure the cathode is water cooled while the high voltage
is on.
Experinmzt.
(1) Evacuate the apparatus
to a very low pressure.
(2) Measure the background scintillations. (3) Turn on the
high voltage, introduce hydrogen and adjust the ow as discussed
above.
This will require experience. (4) Count the number Of
scintillations per
unit time and subtract the background count.
The additional counts are due to the 8.3 centimeter (range) alpha
particles from lithium-seven, as discussed in section 14—15. If a
shallow ionization chamber and amplier is available, this should
be used instead of the scintillation screen.
REFERENCES
1. Rutherford, Phil. Mag., 37, 581 (1919).
2. General reference G, pages
284—301.
3. Blackett, Proc. Roy. Soc., Algä),
349 (1925).
3.
Roy. Soc., A135, 48 (1932).
Kane,
Phys. Rev., 52, 266 (1937).
6. Duncanson and Miller, Proc. Roy. Soc., 146, 396 (1904)7. Pollard and Braseeld, Phys. Rev., 50, 890 (1936).
8. Bothe and Becker, Zeits. f. Physik, 66, 289 (1930)—
_
9. Curie and ]oliot, Compt. Rendus, 194, 273, 708, 876 (1932)10. Chadwick, Proc. Roy. Soc., 136, 692 (1932).
REFERENCES
339
istic green color produced by X—rays. A controlled leak of hydro—
gen
from a tank of this gas would be better than the system de—
scribed, but more complicated.
Unless the cathode C, gure 10—12, is water cooled, it will over…
heat and emit gases which not only lower the voltage but also
introduce undesirable ions in the bombarding beam, and the heat
may melt the wax holding the discharge tube to the cathode.
Premziom.
(1) The observation end must be the grounded
side of the high voltage system and must be kept grounded at all
times, as in gure 10—12. A small static spark, of no serious
danger, may be picked up
from the target tube even though it is
grounded; hence, touch this tube with your hand before looking
into the eyepiece.
(2) Keep away from the anode end of the tube at all times.
(3) Do not operate the apparatus
for too long a period of time
because of the x-rays produced at the anode.
(4) Be sure the cathode is water cooled while the high voltage
is on.
Experinmzt.
(1) Evacuate the apparatus
to a very low pressure.
(2) Measure the background scintillations. (3) Turn on the
high voltage, introduce hydrogen and adjust the ow as discussed
above.
This will require experience. (4) Count the number Of
scintillations per
unit time and subtract the background count.
The additional counts are due to the 8.3 centimeter (range) alpha
particles from lithium-seven, as discussed in section 14—15. If a
shallow ionization chamber and amplier is available, this should
be used instead of the scintillation screen.
REFERENCES
1. Rutherford, Phil. Mag., 37, 581 (1919).
2. General reference G, pages
284—301.
3. Blackett, Proc. Roy. Soc., Algä),
349 (1925).
3.
Roy. Soc., A135, 48 (1932).
Kane,
Phys. Rev., 52, 266 (1937).
6. Duncanson and Miller, Proc. Roy. Soc., 146, 396 (1904)7. Pollard and Braseeld, Phys. Rev., 50, 890 (1936).
8. Bothe and Becker, Zeits. f. Physik, 66, 289 (1930)—
_
9. Curie and ]oliot, Compt. Rendus, 194, 273, 708, 876 (1932)10. Chadwick, Proc. Roy. Soc., 136, 692 (1932).