<< Chapter < Page Chapter >> Page >

Alpha, beta, and gamma

Research begun by people such as New Zealander Ernest Rutherford soon after the discovery of nuclear radiation indicated that different types of rays are emitted. Eventually, three types were distinguished and named alpha α size 12{ left (α right )} {} , beta β size 12{ left (β right )} {} , and gamma γ size 12{ left (γ right )} {} , because, like x-rays, their identities were initially unknown. [link] shows what happens if the rays are passed through a magnetic field. The γ size 12{γ} {} s are unaffected, while the α size 12{γ} {} s and β size 12{β} {} s are deflected in opposite directions, indicating the α size 12{α} {} s are positive, the β size 12{β} {} s negative, and the γ size 12{γ} {} s uncharged. Rutherford used both magnetic and electric fields to show that α size 12{α} {} s have a positive charge twice the magnitude of an electron, or + 2 q e size 12{+2 lline q rSub { size 8{e} } rline } {} . In the process, he found the α size 12{γ} {} s charge to mass ratio to be several thousand times smaller than the electron’s. Later on, Rutherford collected α size 12{γ} {} s from a radioactive source and passed an electric discharge through them, obtaining the spectrum of recently discovered helium gas. Among many important discoveries made by Rutherford and his collaborators was the proof that α size 12{γ} {} radiation is the emission of a helium nucleus . Rutherford won the Nobel Prize in chemistry in 1908 for his early work. He continued to make important contributions until his death in 1934.

The figure shows north and south poles of a magnet through which three rays labeled as alpha beta and gamma are passed. After passing through a magnetic field the alpha ray is slightly deflected toward the right. The beta ray is deflected toward the left and the gamma ray is not deflected.
Alpha, beta, and gamma rays are passed through a magnetic field on the way to a phosphorescent screen. The α size 12{γ} {} s and β size 12{β} {} s bend in opposite directions, while the γ size 12{γ} {} s are unaffected, indicating a positive charge for α size 12{γ} {} s, negative for β size 12{β} {} s, and neutral for γ size 12{γ} {} s. Consistent results are obtained with electric fields. Collection of the radiation offers further confirmation from the direct measurement of excess charge.

Other researchers had already proved that β size 12{β} {} s are negative and have the same mass and same charge-to-mass ratio as the recently discovered electron. By 1902, it was recognized that β size 12{β} {} radiation is the emission of an electron . Although β size 12{β} {} s are electrons, they do not exist in the nucleus before it decays and are not ejected atomic electrons—the electron is created in the nucleus at the instant of decay.

Since γ size 12{γ} {} s remain unaffected by electric and magnetic fields, it is natural to think they might be photons. Evidence for this grew, but it was not until 1914 that this was proved by Rutherford and collaborators. By scattering γ size 12{γ} {} radiation from a crystal and observing interference, they demonstrated that γ size 12{γ} {} radiation is the emission of a high-energy photon by a nucleus . In fact, γ size 12{γ} {} radiation comes from the de-excitation of a nucleus, just as an x ray comes from the de-excitation of an atom. The names " γ size 12{γ} {} ray" and "x ray" identify the source of the radiation. At the same energy, γ size 12{γ} {} rays and x rays are otherwise identical.

Properties of nuclear radiation
Type of Radiation Range
α size 12{α} {} -Particles A sheet of paper, a few cm of air, fractions of a mm of tissue
β size 12{β} {} -Particles A thin aluminum plate, or tens of cm of tissue
γ size 12{γ} {} Rays Several cm of lead or meters of concrete

Ionization and range

Two of the most important characteristics of α size 12{α} {} , β size 12{β} {} , and γ size 12{γ} {} rays were recognized very early. All three types of nuclear radiation produce ionization in materials, but they penetrate different distances in materials—that is, they have different ranges . Let us examine why they have these characteristics and what are some of the consequences.

Questions & Answers

a car move 6m. what is the acceleration?
Umaru Reply
depends how long
What is the simplest explanation on the difference of principle, law and a theory
Kym Reply
how did the value of gravitational constant came give me the explanation
Varun Reply
how did the value of gravitational constant 6.67×10°-11Nm2kg-2
A steel ball is dropped onto a hard floor from a height of 1.50 m and rebounds to a height of 1.45 m. (a) Calculate its velocity just before it strikes the floor.
Kris Reply
0.5m* mate.
0.05 I meant.
Guess your solution is correct considering the ball fall from 1.5m height initially.
How can we compare different combinations of capacitors?
Prakash Reply
find the dimension of acceleration if it's unit is ms-2
Happiness Reply
b=-2 ,a =1
M^0 L^1T^-2
what is botany
it is a branch of science which deal with the study of plants animals and environment
what is work
Sunday Reply
a boy moving with an initial velocity of 2m\s and finally canes to rest with a velocity of 3m\s square at times 10se calculate it acceleration
6.6 lol 😁😁
show ur work
sorry..the answer is -10
your question is wrong
If the boy is coming to rest then how the hell will his final velocity be 3 it'll be zero
re-write the question
men i -10 isn't correct.
using v=u + at
ya..1/10 is very correct..
how did the value 6.67×10°-11Nm2kg2 came tell me please
Work is the product of force and distance
what is longitudinal wave
Badmus Reply
A longitudinal wave is wave which moves parallel or along the direction of propagation.
longitudinal wave in liquid is square root of bulk of modulus by density of liquid
Is British mathematical units the same as the United States units?(like inches, cm, ext.)
Nina Reply
We use SI units: kg, m etc but the US sometimes refer to inches etc as British units even though we no longer use them.
Thanks, just what I needed to know.
What is the advantage of a diffraction grating over a double slit in dispersing light into a spectrum?
Uditha Reply
can I ask questions?
Boniface Reply
hello guys
when you will ask the question
anybody can ask here
is free energy possible with magnets?
you could construct an aparatus that might have a slightly higher 'energy profit' than energy used, but you would havw to maintain the machine, and most likely keep it in a vacuum, for no air resistance, and cool it, so chances are quite slim.
calculate the force, p, required to just make a 6kg object move along the horizontal surface where the coefficient of friction is 0.25
Yes ask
if a man travel 7km 30degree east of North then 10km east find the resultant displacement
Ajali Reply
disagree. Displacement is the hypotenuse length of the final position to the starting position. Find x,y components of each leg of journey to determine final position, then use final components to calculate the displacement.
1.The giant star Betelgeuse emits radiant energy at a rate of 10exponent4 times greater than our sun, where as it surface temperature is only half (2900k) that of our sun. Estimate the radius of Betelgeuse assuming e=1, the sun's radius is s=7*10exponent8metres
James Reply
2. A ceramic teapot (e=0.20) and a shiny one (e=0.10), each hold 0.25 l of at 95degrees. A. Estimate the temperature rate of heat loss from each B. Estimate the temperature drop after 30mins for each. Consider only radiation and assume the surrounding at 20degrees
Is our blood not red
Aditya Reply
If yes than why when a beam of light is passing through our skin our skin is glowing in red colour
because in our blood veins more red colour is scattered due to low wavelength also because of that scattered portion comes on skin and our skin act as a thinscreen.
so you saying blood is not red?
blood is red that's why it is scattering red colour!
like if u pass light frm red colour solution then it will scatter red colour only.. so same it is with our skin..red colour blood is moving inside the veins bcz of thinkness of our fingers.. it appears to be red.
No I am not saying that blood is not red
then ur qtn is wrong buddy.. 😊
Blood is red. The reason our veins look blue under our skin, is because thats the only wavelength on light that can penetrate our skin.
Red light is reflected from our blood but because of its wavelength it is not seen. While in the other hand blue light has a longer wavelength allowing it to pass the our skin and to our eyes.
Thus, our veins appear blue while they are really red... THE MORE YOU KNOW...(;
So in conclusion our blood is red but we can only see blue spectrum because of our skin. The more longer a wavelength is the more durable it is to reflection, so blue light cant pass thew skin completely causing a reflection which causes veins to appear blue. While the red light is scatter around.
the reason why when we shine a light at our skin it appears red is because the red light is increased and more goes to your eyes. So in other words it increases the amount of red light vs it being scatterd around everywhere.
I think the blood is only a mixture of colors but red is predominant due to high level of haemoglobin.
As a side note, the heme part of hemoglobin is why blood is red
a car starts from rest acceleration and moves with a uniform acceleration a, in time t. the distance covered during the motion is expressed as?.
Ifetomide Reply
Practice Key Terms 8

Get the best College physics course in your pocket!

Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'College physics' conversation and receive update notifications?