# 31.1 Nuclear radioactivity  (Page 2/12)

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## 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 $\left(\alpha \right)$ , beta $\left(\beta \right)$ , and gamma $\left(\gamma \right)$ , because, like x-rays, their identities were initially unknown. [link] shows what happens if the rays are passed through a magnetic field. The $\gamma$ s are unaffected, while the $\alpha$ s and $\beta$ s are deflected in opposite directions, indicating the $\alpha$ s are positive, the $\beta$ s negative, and the $\gamma$ s uncharged. Rutherford used both magnetic and electric fields to show that $\alpha$ s have a positive charge twice the magnitude of an electron, or $+2\mid {q}_{e}\mid$ . In the process, he found the $\alpha$ s charge to mass ratio to be several thousand times smaller than the electron’s. Later on, Rutherford collected $\alpha$ 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 $\alpha$ 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.

Other researchers had already proved that $\beta$ 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 $\beta$ radiation is the emission of an electron . Although $\beta$ 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 $\gamma$ 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 $\gamma$ radiation from a crystal and observing interference, they demonstrated that $\gamma$ radiation is the emission of a high-energy photon by a nucleus . In fact, $\gamma$ radiation comes from the de-excitation of a nucleus, just as an x ray comes from the de-excitation of an atom. The names " $\gamma$ ray" and "x ray" identify the source of the radiation. At the same energy, $\gamma$ rays and x rays are otherwise identical.

$\alpha$ -Particles A sheet of paper, a few cm of air, fractions of a mm of tissue
$\beta$ -Particles A thin aluminum plate, or tens of cm of tissue
$\gamma$ Rays Several cm of lead or meters of concrete

## Ionization and range

Two of the most important characteristics of $\alpha$ , $\beta$ , and $\gamma$ 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.

Describe an experiment to determine short half life
what is science
A 20MH coil has a resistance of 50 ohms and us connected in series with a capacitor to a 520MV supply
what is physics
it is the science which we used in our daily life
Sujitha
Physics is the branch of science that deals with the study of matter and the interactions it undergoes with energy
Junior
it is branch of science which deals with study of happening in the human life
AMIT
it is when you get up of your arse and do some real work 😁
A 20MH coil has a resistance of 50 ohms and is connected in series with a capacitor to a 250MV supply if the circuit is to resonate at 100KHZ, Determine 1: the capacitance of the capacitor 2: the working voltage of the circuit, given that pie =3.142
Musa
Heat is transfered by thermal contact but if it is transfered by conduction or radiation, is it possible to reach in thermal equilibrium?
Yes, It is possible by conduction if Surface is Adiabatic
Astronomy
what are the fundamentals qualities
what is physic3
Kalilu
what is physic
Kalilu
Physics? Is a branch of science dealing with matter in relation to energy.
Moses
Physic... Is a purging medicine, which stimulates evacuation of the bowels.
Moses
are you asking for qualities or quantities?
Noman
give examples of three dimensional frame of reference
your fat arse sitting all day is a good reference of three dimensional numbnut
Universe
Noman
Yes the Universe itself
Astronomy
Examine different types of shoes, including sports shoes and thongs. In terms of physics, why are the bottom surfaces designed as they are? What differences will dry and wet conditions make for these surfaces?
sports shoes are designed in such a way they are gripped well with your feet and their bases have and high friction surfaces, Thong shoes are for comfort, these are easily removed and light weight. these are usually low friction surfaces but in wet conditions they offer greater friction.
Noman
thong sleepers are usually used in restrooms.
Noman
what is wave
The phenomenon of transfer of energy
Noman
how does time flow in one dimension
you mean in three dimensions......numbnut
yeah that was a mistake
Lord
if it flows in three dimensions does it mean if an object theoretically moves beyond the speed of light it won't experience time
Lord
time seems to flow in one direction...but I the past present and future happen every moment time flies regardless.
but if an object moves beyond the speed of light time stops right for it
Lord
yes but at light speed it ceases
Lord
yes it always flow from past to future.
Noman
if v=ktx Ly Mz find the value of x,y and z
x=v=ktx Ly Mz find the value of x,y and z
y=v=ktx Ly Mz find the value of x,y and z
z=v=ktx Ly Mz find the value of x,y and z
now get your lazy arse up and clean the kitchen 😁
I want to join the conversation
😂
hmm
Stephen
what conversation you talking about? .....numbnut
how do i calculate for period of the oscillation
T=2π√(m÷k).K is spring constance
Ambe
T=2π√m/k
Lord
does the force in a system result in the energy transfer?
full meaning of GPS system
global positioning system
Noman
what's the use of the GPS
Matthew