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Questions tagged [radioactivity]

The property of some materials by which individual atoms decay, emitting energy or particles often transforming into different elements in the process.

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What is wrong with my Cloud Chamber? I can't see supersaturated vapor or particles [duplicate]

I'm using black felt at the bottom, a small tin can, and black sponge around the inside of the can. I hot glued them onto the can, and then put 91% isopropyl alcohol in it. Afterwards, I used some ...
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3answers
10k views

How does the Earth's center produce heat?

In my understanding, the center of the Earth is hot because of the weight of the its own matter being crushed in on itself because of gravity. We can use water to collect this heat from the Earth and ...
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1answer
59 views

Why is the isotope of lead-206 stable against alpha decay?

The mass of Lead-206 is larger than that of Mercury-202 + Helium-4. Why is then Lead-206 stable against alpha decay? I have heard that the beta-decay can stabilize a nucleus against alpha decay, and ...
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5answers
500 views

Probability of decay of a nucleus

Question: A given sample of radium-226 has a half life of 4 days. What is the probability that a nucleus disintegrates after 2 half lives? Attempt at solution: After time $t$, the number of ...
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Confusion in Positron Decay

As we know, in a positron decay, by the involvement of weak forces, a proton converts into an neutron, emitting a neutrino and a positron, all of this happens inside the nucleus. Why doesn't the ...
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5answers
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Why do unstable nuclei form?

Why do unstable nuclei form? Is it that we simply find unstable nuclei in nature and understand what these nuclei do in order to become more stable? I feel like textbooks gloss over this question ...
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37 views

Speed of beta-decay ejected electrons

It is well known that the energy spectrum of the beta-decay electron is continuous; it was confirmed by the Ellis and Wooster 1927 experiment. It means the electron are ejected with speeds that may ...
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is the half-life of a radioactive isotope dependent on the type of radiation it releases (alpha/beta/gamma)?

I understand the term half-life but I am not sure if the type of radiation it emits is a factor affecting an isotopes half-life
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2answers
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Limit to number of neutrons in nucleus [duplicate]

As far as I understand the number of protons in a nucleus is limited because Coulomb forces grow faster with the number of protons than the nuclear force. So alpha/cluster decay limits the size in ...
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1answer
39 views

Nuclear Propulsion

I am watching a video on nuclear rocket engines, specifically the Nerva engine. It has a propulsion efficiency of 750-800 Isp versus chemical rockets which are only 350-400 Isp. The follow on NRX ...
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0answers
30 views

Tritium decay energy too small for quark model

So $^3$H turns into $^3$He through $\beta^-$ decay, right? The energy of this reaction is only 18.6 keV. However, according to the constituent quarks model, the only thing different between $^3$H ...
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2answers
51 views

Why is energy released during fission reactions?

If the energy released during a fission reaction is the binding energy then what energy is left to bind the nucleons together? I'm very confused if there's a better explanation on fission I'd ...
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What exactly is binding energy?

I've been reading on radioactivity but along the way I got confused, if binding energy is the amount of energy used in holding the nucleus together then why is binding energy also the amount of energy ...
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39 views

Half thickness of lead using a Ba-133m source, references?

I carried out an experiment to calculate the half thickness (half value layer) of lead. The experiment was done using what i believe to be a Ba-133m source on this software: https://radiation-lab....
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1answer
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Why does a single X-ray photon generate 1620 electrons when it hits CCD detector?

Fe55 is one radioactive isotope. It emits X ray photons : mainly k-alpha & k-beta lines. Why does a single X-ray photon generate 1620 electrons when it hits CCD detector ? While, in photo-...
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3answers
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Natural log of 2 in Radioactivity half life?

How exactly was the half life equation $\frac{ln2}{\lambda}$ derived? My book states something about integrated rate laws but doesn't really explain anything. Sorry, this is my first post in Physics ...
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1answer
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The law of radioactive decay: explanation of a formula

The law of radioactive decay can be expressed in terms of $\,\tau=1/\lambda$ (average life) as: $$ N(t)=N_0e^{-t/\tau}, \quad \tag{1} $$ Why deriving the (1) I ...
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1answer
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What exactly is delta-14C and why are there periodic plateaus in the delta-14C curve?

I downloaded the IntCal13, IntCal09, and IntCal04 datasets (parent site), and when I plotted the last 24k years was surprised to see a plateau or even reversal appear every ~5300 years. Apparently we ...
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2answers
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Why is a delta resonance decay not a radioactive decay

A delta resonance decays as given in http://hyperphysics.phy-astr.gsu.edu/hbase/Particles/delta.html . I wonder, why is it not a radioactive decay? In principle, most/all decays should be radioactive ...
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Are human beings radioactive?

I am reading "The greatest story ever told - so far" by Lawrence Krauss. He starts chapter 9, Decay and Rubble, telling how he was shocked when he realized that humans are radioactive. When I first ...
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1answer
294 views

Possible to detect presence of nuclear bomb? [closed]

Take, for instance, a W-80 nuclear warhead. Does technology exist, say in the form of a satellite or drone, that could detect the warhead's presence (assuming it's not enclosed in some kind of ...
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2answers
79 views

How is Electron emitted in a Beta Decay? [closed]

In a beta decay , a neutron converts into proton and an electron. By How is one extra electron created? Are two electrons created by one neutron?
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1answer
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penetration of Fe55 X-ray photons through glass

Can X-ray photons from Fe55 (one radioactive isotope of iron) pass through glass ?
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55 views

Gamma from U238 decay chain

Where can I find detailed information on the gamma background from the U238 decay chain? Edit: Thank you for your replies. I need to find all the branching ratios and extract information of all the ...
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1answer
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Why do half lives of Carbon isotopes vary by a great extent?

Both Carbon-14 and Carbon-15 decay by the $\beta^-$ mechanism but the half life for $C^{14}$ is approximately 5500 years whereas that if $C^{15}$ is around 2 seconds.What causes this disparity in ...
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Has there been any R&D(let alone progress) in the development of gamma voltaic cells?

I ask this because it is my understanding that gamma rays form ion tracks and oxygen radicals when gamma emitting material is immersed in an aqueous solution. Cesium-137 is a very strong gamma ray ...
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1answer
33 views

Gamma spectrometry: effect on one peak when adding another source

Suppose I have a sample containing only 137Cs. Now assume it shows 1000 cps counts for 137Cs, 662keV energy. Now I added 60Co (1173, 1332 keV) source in the same sample. Compton scattering ...
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Questions regarding germanium detector

Why n+ contact in n type Ge is not several hundred microns? . Why we require both additional p or n type contact? in p type Ge, why we require additional p type junction also? crystal itself should ...
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2answers
58 views

How to derive the allowed beta decay selection rule $\Delta L=0$?

Starting from the beta decay matrix element and Fermi's golden rule how can one show that the matrix element at the leading order vanishes unless $\Delta L=0$?
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1answer
50 views

Talking Radon: Activity or Concentration

Currently I'm working on my PhD in environmental sciences and we are measuring Radon-222 in air using a commercially available detector. The results from the detector are given in units Becquerel per ...
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0answers
26 views

Is synchronized radiation possible?

Could it be possible to make 2 or more radioactive atoms, maybe plutonium, emit radiation at the same time? A kind of synchronized radiation. Perhaps this can be the basis for some kind of laser too.
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0answers
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I have proved that radioactive disintegration is first order using probability. Is my proof correct? [closed]

I am a high school student and this is just a small attempt to prove why radioactive disintegration is first order. I don't even know if it has already been proved or not. Please let me know. I later ...
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2answers
36 views

Can't see any traces of particles in my Wilson chamber without radioactive material

I am doing an essay about particle physics and I need some help. I am comparing the results in a Wilsonchamber with and without a radioactive material present. I were able to see a lot of traces from ...
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6answers
125 views

Does the half-life of an element mean it will never decay completely?

Example: Half life of Polonium-194 is 0.7 seconds. If we supposedly take 50g of Polonium, there will surely be a time when no more of this Polonium will be left because if we consider the decay ...
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2answers
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Theoretical explanation behind alpha particle emission [duplicate]

I have started studying radioactive decay. When I studied alpha-particle emission from an unstable nucleus I wondered why should there be emission of helium nucleus only(alpha particle) and why not ...
3
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1answer
84 views

Nuclear reaction – What is the asterisk an indication of?

I've been observing the two-step decay of iodine-131 and can't quite determine what the asterisk above Xenon-131 indicates. I'm currently unsure as to what precisely the superscript asterisk on Xenon ...
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1answer
49 views

How to interpret the radioactivity for a radioactive material that generate isotopes?

I have a Strontium-90 radioactive source. The radioactivity of this source is $0.1\mu\ \rm Ci$. This source $\beta$−decays into Yttrium-90. Then Yttrium-90 $\beta$−decays into Zirconium-90 with a ...
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0answers
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Why is Neon not used as a coolant for gas cooled nuclear reactors?

What is the reason that Neon is not considered as good coolant for gas cooled reactors? I haven't found any research nor experiment with Neon in this field. As I checked out Neon has small neutron ...
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1answer
22 views

In a Radioisotope betavoltaic cell, does the amperage or voltage decay?

In a tritium-powered betavoltaic cell, the power output obviously decreases as the tritium decays. Is it the voltage, amperage, or both that would decay?
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1answer
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Question relating to storage of radioactive substances

I saw this para while reading my physics textbook which said that radioactive substances were kept in thick lead containers with a very narrow opening. I understood the purpose of the lead but what is ...
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2answers
529 views

What is the mean life of a radioactive substance?

As far as my understanding goes, it is the average lifetime of a collection of nuclei undergoing disintegration. But doesn't each nucleus take an infinite amount of time to decay? Is that not why we ...
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2answers
54 views

Link between average lifespan and half time in radioactivity

I have learnt that in radioactivity $λ=\ln2/t_{1/2}$, thus showing the link between λ and radioactive half time. I have also learnt how to apply it in calculations (such as $R={R_0}e^{-λt}$) etc. Now ...
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2answers
167 views

How much do radiation-resistant suits cost?

Let's say you wanted a top-of-the-line, impenetrable suit to withstand high levels of radiation. How much does one of these suits cost?
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1answer
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Unstable vs. stable nuclei plotted on a graph

The enclosed graph shows the number of Protons on the x-axis (Z), and the number of Neutrons on the y-axis for all elements (N). Stable combinations are marked by black squares, whereas unstable ones ...
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3answers
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What happens to a radioactive material's atom when it disintegrates?

Suppose you initial had radioactive $2^n$ atoms (where $n$ is an integer). Now after a number of halflives the number of left out atoms becomes 1. Now what will happen to it will it disintegrate and ...
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3answers
3k views

Why do some gases transfer radioactivity and some don't?

I have recently read that helium is going to be used as coolant in Generation IV nuclear reactors, because Helium is radiologically inert (i.e., it does not easily participate in nuclear processes ...
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2answers
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What's wrong with the following way to calculate mean lifetime from half-life?

So I understand that half-life $T_{1/2}$ is the time for the amount $N(0)$ to reduce by half. Basically, $$N(t)=N(0)2^{-t/T_{1/2}} $$ My question is that why can't I use this to directly pull out the ...
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2answers
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What is the reason for radioactivity?

In any radioactive series we can observe that the half-lives of a daughter nucleus might be less than that of the parent nucleus. If the reason for radioactivity is gaining stability, why does a more ...
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0answers
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Is this samarskite producing Xe-135?

I left a small sample of samarskite (a uranium bearing mineral) directly beside a radiation monitor for a few days as in the photo below. I then removed the samarskite, left the radiation monitor in ...
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2answers
132 views

Is there a way to slow down radioactive decay? (with mathematical proof)

See http://wtamu.edu/~cbaird/sq/2015/04/27/can-the-decay-half-life-of-a-radioactive-material-be-changed/ It stated that relativistic effect(obviously) and chemical component can slow down the radio ...