 |
Link:
Back Contents Next
4.2. Experiments with gamma rays
At present time it is considered, that because of weak absorption
of gamma quanta by air those gammas propagate through air in such a way that
air molecules do not participate in transmission of gamma quanta from one point of space
to another one by means of their absorption and subsequent retransmission. This situation
allows carrying out experiments with moving sources of gamma quanta not in vacuum, but at
normal atmospheric pressure of air, sufficiently facilitating experiment realisation.
Besides, the sources of gamma quanta can move at considerably greater speeds of motion
than mirrors. This allows using for measuring experiment results time of gammas flight
through a certain distance instead of interference phenomenon, as a result the execution
of experiments is also sufficiently facilitated .
The experiments with gamma quanta are as follows:
- [[37]. Alvager T., Nilsson A.,
Kjellman J. On the independence of the velocity of light of the motion of the light source
// Arkiv fur Fysik. - 1964.- B. 26.-No. 16. - S. 209-221; A direct terestrial test of the
second postulate of special relativity // Nature. - 1963. -v. 197. -p.1191.];
- [ [38]. Sadeh D.
Experimental evidence for the constancy of the velocity of gamma rays, using annihilation
in flight // Physical Review Letters. – 1963 .-v. 10. - p. 271 - 273.];
- [ [39]. Fillipas T. A., Fox
J. G. Velocity of gamma rays from a moving source // Physical Review. - 1964. - v. 135.-p.
1075];
- [ [40]. Test of the
second postulate of special relativity in the GeV region / Alvager T., Farley F., Kjellman
J., Wallin J. // Physical Letters. - 1964. - v. 12. –No. 3. - p. 260 -262.].
Experiment with alpha particles by Alvager, Nilsson and Kjellman [37]
In the experiment [ [37].
Alvager T., Nilsson A., Kjellrian J. On the independence of the velocity of light of the
motion of the light source // Arkiv fur Fysik. - 1964.- B. 26.-No. 16. - S. 209-221; A
direct terestrial test of the second postulate of special relativity // Nature. - 1963.
-v. 197. -p.1191] targets made of carbon С12
and oxygen О16 were bombarded by alpha particles with kinetic
energy of 14 MeV accelerated in a cyclotron. In the result of such bombardment, excited
nuclei with a certain recoil speed appeared. Excited carbon nuclei radiate gamma
quanta before they come to a standstill having a speed of 0.018 сo
measured using doppler shift of frequency. And oxygen nuclei radiate gamma quanta after
they come to a standstill (doppler frequency shift was not detected). Radiated gamma
quanta were received by two detectors. The first one was placed at a distance of 1 meter
from the targets, and the second one was placed on the same line with the first detector
at a distance of 5 m from the targets. The targets were placed at a distance of 30 cm one
from other and it was possible to change their places quickly.
In this experiment the time moment of gamma quanta passage through the
detectors were measured and after that experimentators calculated the value
D = { [ (t2O16-
t1O16) - (t2С12-
t1С12) ] - [ (t2O16
- t1O16) - (t2С12- t1С12)
] } , (4.6)
where t1, t2 are measured moments of
gamma quanta hitting into the first and into the second detectors, respectively, in a case
when alpha particles fly at first through the oxygen target and then through the carbon
target; t1, t2 are
measured moments of gamma quanta hitting into the first and into the second
detectors, respectively, in a case when alpha particles at first fly through the
carbon target and then through the oxygen target, and the upper index shows which of
nucleus the detected gamma quantum was radiated.
If you will determine the moments of gamma quanta hittings into
detectors, then using known distance between the detectors and the supposed speeds of
gamma quanta, instead of expression (4.6) you will have
D = 2 s (co-1- cu-1),
(4.7)
where s = 4 m is a distance between the
detectors; co is speed of gamma quanta
radiated by immovable oxygen nuclei; cu is speed of
gamma quanta radiated by moving carbon nuclei.
Substituting expression (4.2) into formula (4.7) we have
D = 2 s k u co-2 ,
(4.8)
where u = 0.018 co
is speed of motion of carbon nuclei; k = 1
if dependence cu = co + u·cosa exists in nature;
k is
determined by expression (4.4) if dependence cu = co·(1 + u2/co2)1/2
exists in nature.
Substituting into expression (4.8) numerical values of magnitudes and
k
= 1, we shall have D(4.1) = 0.5
10-9 seconds, corresponding to existence in nature of dependence
cu =
co + u cosa. Substituting
into expression (4.8) numerical values of magnitudes and value k
from expression (4.4), we shall have D(2.1) = 0.5
10-11 seconds corresponding existence in nature of dependence
cu = co(1 + u2/co2)1/2.
The value Dexp
calculated according to formula (4.6) and measured in the experiment [37] moments of gamma
quanta hitting into detectors after statistical processing is equal to Dexp = (0.2 ± 0.2) 10-9 seconds.
So, because of the result Dexp < D(4.1), experiment [37] prooves that
dependence cu = co + u cosa is absent in real nature.
But dependence cu = co(1 + u2/co2)1/2
is neither confirmed nor disproved by the experiment [37] too. It is conditioned by the
fact that root-mean-square error of measuring the value Dexp,
which in this experiment is equal to 0.2 nanoseconds, is two orders (100 times)
greater than the value D(2.1)
resulting from the dependence cu = co(1 + u2/co2)1/2.
Experiment [37] has one more drawback - gamma quanta hitting into
the second detector come through the substance of the first detector. Therefore one can
suppose that gamma quanta coming to the second detector are not primary gamma quanta
radiated in the targets, but secondary gamma quanta re-radiated by the substance of
the first detector. If this effect exist in reality, then experiment [37] has no probative
force with respect to dependence cu = co + u cosa too.
Experiment with positrons by Sudeh [38]
In
the experiment [ [38]. Sadeh D. Experimental evidence
for the constancy of the velocity of gamma rays, using annihilation in flight // Physical
Review Letters. – 1963 .-v. 10. - p. 271 - 273.] a
beam of positrons was directed to a target of 1 mm thickness made of acrylic plastic. In
this target the annihilation of positrons with electrons being components of acrylic
plastic target occurs. Two gamma quanta appearing at annihilation fly away at an
angle of 180° in the
positron and electron centre-of-mass system, and at less angle, depending upon the
positron momentum, in the laboratory system. In experiment [38] two detectors
of gamma quanta were placed at the same distance (equal to 60 cm) from targets in
directions making up angles of 20° and 135° with the direction of positrons flight. Under such conditions the
detectors detected only those gamma quanta, which were formed at a certain speed of motion
of the electron-positron system centre of mass equal to approximately 0.6·co .
Special electronic circuit provided measuring the difference in time between registration
of these gamma quanta by the detectors with an accuracy of 0.2 10-9 seconds. Within the limits of measuring errors any difference in
time of gamma quanta registration in the experiment [38] was not detected, whereas, if
dependence cu = co + u cosa exists in nature, between the
moments of gamma quanta hitting into the detectors a time interval of the order 0.2·10-9 seconds
should be observed. So, experiment [38] reliably confirmed the absence in nature of
dependence cu = co + u cosa.
As to the dependence cu = co·(1 + u2/co2)1/2, the experiment [38] does not disprove it, and can not disprove it
in principle (even if the accuracy of measuring the difference between the moments of
gamma quanta registration by the detectors will be some orders greater). This is
conditioned by the fact that according to the formula cu = co(1 + u2/co2)1/2 the speed of light depends only upon absolute (modulus) of the
source velocity vector, and does not depend upon an angle between a direction of a source
motion and a direction of gamma quanta motion. Indeed, if the dependence cu = co(1 + u2/co2)1/2 exists in nature, then gamma quanta must hit detectors
simultaneously, if they were emitted simultaneously from a point equidistant from the
detectors .
Experiment
by Fillipas and Fox [39]
Just because of the same reason the experiment [ [39]. Fillipas T. A., Fox J. G. Velocity of gamma rays from a
moving source // Physical Review. - 1964. - v. 135.-p. -1075] also can not disprove in principle the existence in nature of the
dependence cu = co(1 + u2/co2)1/2. In experiment [39] the experimentators checked simultaneity of
gamma quanta (appearing at decay of neutral pi-mesons) hitting detectors placed
equidistantly from a point, in which the gamma quanta were born. But absence in
nature of dependence cu = co + u cosa the experiment [39] prooves with
high degree of reliability.
Link: Back
Contents Next
|  |