Radiation is a process in which energetic particles or energetic waves travel through a medium or space. The particles or waves radiate (i.e., travel outward in all directions) from a source.

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How to calculate absorbed dosage

Lets say you have some unstable isotope which decays via beta decay. For example, lets say you want to calculate the amount of beta radiation that is emitted from the decay of $^{87}\textrm{Kr}\to ^{...
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How is the amount of radiation calculated from a decay?

Lets say you have some unstable isotope which decays via beta decay. For example, lets say you want to calculate the amount of beta radiation that is emitted from the decay of $^{87}\textrm{Kr}\to ^{...
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78 views

Why Doesn't Einstein Get More Credit for Being the Father of Quantum Theory? [on hold]

I'm not simply referring to the notion that Einstein treated the discrete emission and transference of energy (and matter) as "real" physical phenomena, but rather his major continuous role in the ...
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Stopping power of charged particles in matter

So I have this diagram of how the stopping power of muons changes with energy: Depending on energy different equations are used to describe the stopping power variation. Now, currently I'm reading ...
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Nuclear bomb power - myth?

I'm not experienced in physics yet (if it helps I've covered as much as acceleration, momentum and energy transfer/chemistry ionic and covalent bonding) but I've heard that the way people compare ...
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1answer
123 views

Purcell's approach to Larmor's formula, assumption?

In 'Electricity and Magnetism' By E.M.Purcell, a derivation is given of Larmor formula (a version of which can be found here). I will give a brief overview here: A particle is considered at ...
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82 views

Trapped in a room with Cobalt 60 - what is the best position to minimize dose?

Been thinking of an old TV series I once saw that involved a man being trapped in a room with a Co60 source of (presumably) high activity. So, assuming no escape and nowhere to throw or hide the Co60, ...
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1answer
38 views

Why does a CfBe neutron source not exist?

Sources such as AmBe take advantage of Beryllium's $(\alpha,n)$ process to produce high energy neutrons. Sources such as Cf utilize spontaneous fission. Why not combine the two? Such a source would ...
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How can there be heat in a vacuum?

I keep reading in the Physics World focus issue on vacuum technology about scientists creating high temperatures in the vacuums etc. If heat is caused by thermal energy being radiated from particles ...
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47 views

Does radiation emission depends upon absorption?

Is it possible that we stop the absorption of radiation completely? if so, will we stop emission from our own body? Does the radiation emission depends upon absorption?
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Would a laser with four possible energy levels be better than three?

I'm wondering about achieving population inversion for a laser. I learned that without an active medium, it's not possible to create a laser with only two energy levels, but it would be possible with ...
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38 views

Why is lead used for X-ray cladding equipment?

I've done some research and can see that the distance travelled by an x-ray through lead is far less than through other materials, but is there a more "full" explanation that I'm missing out on to do ...
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41 views

How does radiative cooling between the earth and space work?

On a chilly (but above freezing) temperatures on a clear night, you can freeze water outside because of radiative cooling. By what mechanism do warm bodies on earth actually lose heat to space? ...
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Would being underwater help survive a nuclear bomb?

If I jump in my pool, on the river near my house knowing that a nuclear bomb, or atomic or H-Bomb exploded around 10 km from my house, would I survive? The way I see it is that water will protect me ...
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74 views

World's Largest Radio Telesope : How accurately does it need to be figured?

In Guizhou Province, China, the worlds largest radio telescope is almost complete, measuring 500 metres across. I am aware that todays largest optical telescope require very accurate figuring and ...
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4answers
2k views

What is happening over the 15 minutes it takes a neutron to decay?

I've read that free neutrons decay into a proton, electron and neutrino with an average lifespan of about 15 minutes. Is there anything physically different about a neutron that has existed for 14 ...
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16 views

Is the decay of nuclei also depending on the 'age' of nuclei or whether they are created or not? [duplicate]

Usually the decay is said to be randomly but the average period of decay of certain atoms are stable. So if you randomly take a bunch of the same atoms the average time before the decay will fe be 5 ...
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1answer
22 views

Dependence of atomic mass number in the Bragg Kleeman rule

I have just staring learning about radioactivity, more or less about alpha particles and how there range can be approximated by the Bragg Kleeman rule, $\displaystyle{R \varpropto \frac{\sqrt{A}}{\rho}...
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Tunneling of alpha particles

Consider this explanation of the alpha decay: It says The Coulomb barrier faced by an alpha particle with this energy is about 26 MeV, so by classical physics it cannot escape at all. ...
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231 views

In the Iranian nuclear deal, how can IAEA detect nuclear activity after 24 days?

This is a question related to current events, but I want to ask about the physics, which are not explained in any news article that I can find. Ernest Moniz and John Kerry wrote an op-ed in the ...
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3answers
897 views

Do human bodies give off a consistent but unique radiation/electromagnetic/energy signature?

Is there any facet of the energy emitted by a human body that is consistent and unique - like a fingerprint, but a signal that could be detected by a remote device?
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2answers
122 views

Where are the photons coming from?

Particles and Antiparticles can annihilate, and they are completely destroyed in the process, which creates photons. From wikipedia: ...
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63 views

Inverse beta decay; energy of anti-neutrino

Assuming that the target protons are at rest, calculate the minimum energy of the anti-neutrino for this reaction to take place: $$\bar{\nu}_e+p\rightarrow e^++n$$ I know the answer is given by $E_{\...
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What temperature can you attain with a solar furnace?

A solar furnace is a device that concentrates the sun's light on a small point to heat it up to high temperature. One can imagine that in the limit of being completely surrounded by mirrors, your ...
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3answers
2k views

Does brightness of the light remains constant with the variation of the distance with respect to the source in vaccum?

I have this question going in my mind from many days, i.e why brightness of light emitted from any light source around us decreases with distance? The brightness of light from tube light, streetlight, ...
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1answer
21 views

Radiation-Glossy Black vs Matte White

Well, studying the chapter Heat I know that a matte black body radiates heat more than a glossy white one but can anyone give me an answer about what happens when its a glossy black body and a dull ...
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1answer
53 views

Would 10 metres of liquid air be as effective against cosmic radiation as Earth's atmosphere? [closed]

Assuming ballpark figures which give a depth of 10m if the Earth's atmosphere was liquefied, would that be as effective a protection against ionizing radiation from space as the gaseous atmosphere is?
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2answers
74 views

What is beyond Gamma Rays and Radiowaves in the Electromagnetic Spectrum?

The electromagnetic spectrum is commonly refered to as consisting of; Radio-waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma Rays - of increasing frequency from left to right. ...
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1answer
55 views

Do all solid objects emit visible light?

Are there solid objects that do not emit visible light? To my limited and humble knowledge, creating such an object would require us to "only" shift the spectrum of emitted radiation. Is it possible? ...
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3k views

Decay of massless particles

We don't normally consider the possibility that massless particles could undergo radioactive decay. There are elementary arguments that make it sound implausible. (A bunch of the following is ...
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15 views

Difference between PIN photodiode and silicon surface barrier in beta spectography

In a physics undergraduate lab we performed an experiment in spectography of beta decay. We used two detectors to measure the energy spectrum of Bi207: PIN photodiode Silicon surface barrier ...
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37 views

Why build so big sarcophagus in Chernobyl instead another alternative? [closed]

As title, why build so big sarcophagus in Chernobyl? The new sarcophagus is really tall, large and expensive and it should cover the old one. But there is already a sarcophagus build over another ...
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0answers
28 views

Bremsstrahlung in body tissue

As far as I know, the intensity of the produced radiation from bremsstrahlung is proportional to: $$I \propto \frac{Z^2}{m^2},$$ where $Z$ is the atomic number, and $m$ is the mass of the particle. ...
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33 views

Diminishing solar temperature and its effects on earth

This is a hypothetical question; considering both the earth and the sun as black bodies. If the temperature of the sun decreased N times, what would be the effect on the radiation intensity received ...
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Do alpha particles add to the mass of the matter they are interacting with?

If a large number of alpha particles are fired into a target material, they presumably interact with the matter by ionisation and eventually lose energy, and are 'absorbed' by the target. Do they ...
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37 views

Does elementary particle decay simply swap mass for speed?

I'm looking at different decays of elementary particles. And I am wondering about the masses (in energy) not matching up. For example, W and Z bosons are far more massive than the particles that decay ...
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1answer
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How to shield myself from the LTE radiation coming from my phone while working on my Laptop? [closed]

I am connecting to the internet with the tethering option on my phone. I wonder if there is a way to shield myself from the LTE radiation (Long-Term Evolution, commonly marketed as 4G) as I am exposed ...
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2answers
35 views

How to combine albedos

I have estimations of the Earth's surface albedo for a region (0.13), as well as an estimation of the atmosphere albedo (0.3 at a solar zenith angle of 1 rad). My question is, how do I find the ...
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1answer
43 views

How much ionizing (carcinogenic) radiation is one exposed to on a commercial flight, what are the sources, and how could exposure be minimized? [closed]

I don't know if this is the best place to ask this question, but I figure a physics-based answer would be the most satisfying. I'd be happy to be convinced I'm being paranoid about protecting an ...
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0answers
60 views

Cherenkov Luminescence Imaging, Cherenkov radiation,

Is it possible to see glowing from Thin Layer chromatography (TLC silica gel on Aluminium) when we image it by IVIS spectrum (no radioactive source)?
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What exactly is the difference between radiation, conduction, and convection?

Okay, so everywhere I've read, I hear the main difference is the requirement of a medium. But for example, if you take the case of heat 'radiating' from a red-hot iron, isn't that actually convection ...
3
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1answer
28 views

Confusion about the shock growth

I am studying Hamilton's & Blackstock's Nonlinear Acoustics. One of the essential phenomena associated with a finite-amplitude (unidimensional, planar) sound propagation is building the shock due ...
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1answer
19 views

Why is beta-minus decay considered isobaric?

Page 20 of Physics in Nuclear Medicine says that beta-minus decay is isobaric (eg the A/Z ratio remains the same). The reason it gives is that "mass number A does not change." However, in beta-minus ...
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3answers
25 views

ionizing radiation and energy

At the website "How Stuff Works" an article (radiation sickness) states that when radiation knocks an electron from an atom, energy (specifically 33 electron volts) is released which heats up the ...
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11 views

Temperature equalization by radiation between two coaxial cylinders - independent of diameters?

Ignoring end effects, assume I have a cylinder of diameter d0 at controlled temperature k0 and then introduce a smaller diameter cylinder of diameter d1 and temperature k1 to the interior. Does the ...
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1answer
23 views

Conceptual Doubt regarding the calculation of the Solar Constant

The Solar constant is the intensity of the solar radiation in the upper atmosphere. It's value is about $1400$ $Wm^{-2}$. Now we begin by stating that the Power radiated by the sun is about $3.9*...
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1answer
37 views

Why beta+- decay occurs?

So nice place to ask question like this here. I have read some basic physics magazine like Newton monthly. There I saw article about nuclei generation in star. I want to know more and found wiki ...
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18 views

Proton Spread Out Bragg Peak vs. lateral beam broadening (Radiotherapy)

I was wondering. When particles enter a medium it has a finite range until it reaches the Bragg Peak where it deposits most of its energy. Now, heavier ions means less lateral broadening of the beam ...
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Why do Photochromatic lenses react to temperature changes?

So, I'm aware that Photochromatic lenses are affected differently due to different ambient temperatures. From what I've read it seems that the molecules rearrange their structures slowly in cold ...
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Does gamma radiation create radioactive people?

I've read that the materials become radioactive. I'm writing a story where an unfortunate person has been in the vicinity of a large amount of gamma radiation. They've absorbed 6-8 Gray. Would the ...