Author Topic: Radiation  (Read 367054 times)

Offline timfinch

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Re: Radiation
« Reply #900 on: April 03, 2018, 01:29:30 PM »
Consider this article from a Nasa web site.

Cosmic ray fluxes, consisting of completely ionized atomic nuclei originating outside the solar system and accelerated to very high energies, provided average dose rates of 1.0 millirads per hour in cislunar space** and 0.6 millirads per hour on the lunar surface. These values are expected to double at the low point in the 11-year cycle of solar-flare activity (solar minimum) because of decreased solar magnetic shielding of the central planets. The effect of high-energy cosmic rays on humans is unknown but is considered by most authorities not to be of serious concern for exposures of less than a few years. Experimental evidence of the effects of these radiations is dependent on the development of highly advanced particle accelerators or the advent of long-term manned missions outside the Earth's geomagnetic influence.

https://history.nasa.gov/SP-368/s2ch3.htm

I am not sure but I think 1 millirad/hour is equal to .24 mgy/day.  Correct me if I am wrong.  This article was written back in the seventies.

Offline timfinch

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Re: Radiation
« Reply #901 on: April 03, 2018, 01:32:05 PM »
Ben, the website graphs the data for you.  You select the parameters and it produces the graph.  Why is it necessary in your mind to re-invent the wheel when the shelves are stocked with wheels?  http://crater-web.sr.unh.edu/products.php?numplots=1&durationtype=span&ProductG111=doserates&SepGcrAllType111=all&InvCombG111=doserates_combined&DaysRangeG111=Alldays&syncdate=yes&StartEndGroup111=end&doy111=085&yeargroup111=2017&s
Yes, it plots the graph for you. Can you not see that the level is below 0.2 mGy/day (i.e. 2 x 10-2 cGy/day on the scale) for the majority of the time?



Do you understand how the logarithmic scale on the vertical axis works? 2 x 10-2 will be log2/log10, or just over 30%, of the way up from 10-2 to 10-1.

The axis is exponential and not logarithmic.  There is a subtle difference recognizable only by high school graduates.

Offline Jason Thompson

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Re: Radiation
« Reply #902 on: April 03, 2018, 01:32:56 PM »
Consider this article from a Nasa web site.

Cosmic ray fluxes, consisting of completely ionized atomic nuclei originating outside the solar system and accelerated to very high energies, provided average dose rates of 1.0 millirads per hour in cislunar space** and 0.6 millirads per hour on the lunar surface. These values are expected to double at the low point in the 11-year cycle of solar-flare activity (solar minimum) because of decreased solar magnetic shielding of the central planets. The effect of high-energy cosmic rays on humans is unknown but is considered by most authorities not to be of serious concern for exposures of less than a few years. Experimental evidence of the effects of these radiations is dependent on the development of highly advanced particle accelerators or the advent of long-term manned missions outside the Earth's geomagnetic influence.

https://history.nasa.gov/SP-368/s2ch3.htm

I am not sure but I think 1 millirad/hour is equal to .24 mgy/day.  Correct me if I am wrong.  This article was written back in the seventies.

Oh how many times? That article quotes an average, NOT the minimum. If you cannot even grasp the difference between those two terms what really is the point?

There is literally no way to soundly and logically interpret that statement to say that minimum GCR flux during Apollo was 0.2mGy/day.
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline Jason Thompson

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Re: Radiation
« Reply #903 on: April 03, 2018, 01:33:58 PM »
The axis is exponential and not logarithmic.  There is a subtle difference recognizable only by high school graduates.

It really isn't, and if you actually did what you have been advised to do and plotted it yourself you would see that with your own eyes. If you just look at the actual numbers you will see how much of it sits below your stated 'minimum' value. WHy will you not do wither of these things? It takes literally five minutes.
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline Luke Pemberton

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Re: Radiation
« Reply #904 on: April 03, 2018, 01:36:50 PM »
Here you go Tim. The blue line is the data, the reddy-brown data is the threshold value of 0.22 mGr day-1.

What you can you say about most the blue data, other than SPE events? Plotted on a log graph for you. I've done nothing with the data.

Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

I can calculate the motion of heavenly bodies, but not the madness of people – Sir Isaac Newton.

A polar orbit would also bypass the SAA - Tim Finch

Offline timfinch

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Re: Radiation
« Reply #905 on: April 03, 2018, 01:38:39 PM »
Consider this article from a Nasa web site.

Cosmic ray fluxes, consisting of completely ionized atomic nuclei originating outside the solar system and accelerated to very high energies, provided average dose rates of 1.0 millirads per hour in cislunar space** and 0.6 millirads per hour on the lunar surface. These values are expected to double at the low point in the 11-year cycle of solar-flare activity (solar minimum) because of decreased solar magnetic shielding of the central planets. The effect of high-energy cosmic rays on humans is unknown but is considered by most authorities not to be of serious concern for exposures of less than a few years. Experimental evidence of the effects of these radiations is dependent on the development of highly advanced particle accelerators or the advent of long-term manned missions outside the Earth's geomagnetic influence.

https://history.nasa.gov/SP-368/s2ch3.htm

I am not sure but I think 1 millirad/hour is equal to .24 mgy/day.  Correct me if I am wrong.  This article was written back in the seventies.

Oh how many times? That article quotes an average, NOT the minimum. If you cannot even grasp the difference between those two terms what really is the point?

There is literally no way to soundly and logically interpret that statement to say that minimum GCR flux during Apollo was 0.2mGy/day.
So he quotes the average at solar maximum and solar minimum and you are claiming what, the Apollo missions dodged the rain drops?  We must deal in averages because anything else would not be possible and we are talking about accumulated dose which is essentially an average.

Offline Luke Pemberton

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Re: Radiation
« Reply #906 on: April 03, 2018, 01:39:47 PM »
It really isn't...

I think he thinks that 1 E-2 means exponential. Is it possible he is confusing capital E used to represent standard form with e, as in 2.718...

Tim, are you aware that 1 E-2 means 1 x 10-2?
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

I can calculate the motion of heavenly bodies, but not the madness of people – Sir Isaac Newton.

A polar orbit would also bypass the SAA - Tim Finch

Offline timfinch

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Re: Radiation
« Reply #907 on: April 03, 2018, 01:41:04 PM »
Here you go Tim. The blue line is the data, the reddy-brown data is the threshold value of 0.22 mGr day-1.

What you can you say about most the blue data, other than SPE events? Plotted on a log graph for you. I've done nothing with the data.

I am like a proud father.  You have grown so much in the last 3 days.  Now that is a logarithmic graph.  Good job.

Offline Luke Pemberton

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Re: Radiation
« Reply #908 on: April 03, 2018, 01:43:19 PM »
We must deal in averages because anything else would not be possible and we are talking about accumulated dose which is essentially an average.

But the CRaTER data does not show that does it. The CRaTER data illustrates that there are windows where the dose over a short time window will be less than the average of thousands of samples, and so does the Chandrayaan data. This is why trying to use averages reported in scientific literature can only be used as a first order approximation at very best.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

I can calculate the motion of heavenly bodies, but not the madness of people – Sir Isaac Newton.

A polar orbit would also bypass the SAA - Tim Finch

Offline BertieSlack

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Re: Radiation
« Reply #909 on: April 03, 2018, 01:44:21 PM »
What human activity remains exist that a machine could not have been the source of?

So you're admitting that Chandrayaan and Zond DID get as far as lunar orbit?

Offline Jason Thompson

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Re: Radiation
« Reply #910 on: April 03, 2018, 01:44:28 PM »
So he quotes the average at solar maximum and solar minimum and you are claiming what, the Apollo missions dodged the rain drops?

I am claiming nothing. I am pointing out where you are making mistakes in interpretation. You claim that article states a minimum. It absolutely does not. And no, Apollo did not 'dodge' anything, because what that doesn't actually provide is any indication of the range of the data used to generate that average.

Quote
We must deal in averages because anything else would not be possible

That is categorically untrue.

Quote
and we are talking about accumulated dose which is essentially an average.

How is accumulated anything an average? You calculate an average from the accumulated dose by dividing it over time.

Have you noticed what happens if you actually look at the daily dose rates for each Apollo mission with this in mind? SOme are higher, some are lower (as expected mathematically), and the avergae daily dose rate across all those missions is higher than the average GCR flux quoted in that article.
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline nomuse

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Re: Radiation
« Reply #911 on: April 03, 2018, 01:44:45 PM »
Nuclear Radiation at the Lunar Surface, Barton -- found in Advances in the Astronautical Sciences vol 6, proceedings of the American Astronautical Society 1960 annual meeting and printed by Macmillan in 1961.

He estimates contribution of the Moon versus both natural radionuclides and secondary radiation activated by "spallation, fission, fragmentation and capture." His estimate is that during a quiet sun what he calls the induced radiation (neutrons, gamma, and protons) would contribute a weekly dose of .5 millirems. The primordial granite and basalt is ALREADY contributing 2.5 millirems.

Now, this was taken before lunar samples had been returned, and the actual neutron value is apparently surprisingly higher. Science marches on. I quote from this book to show:

1) The secondary radiation was described publicly years before the Apollo flights.

2) The secondary radiation could be derived by anyone from first principles; it didn't need spacecraft to go out and look and since any college physics student could do it, it isn't something that can be or was hidden.

3) Physicists clearly separate the short-duration secondary activation from long-lived radioisotopes.

4) The human effect we are talking about is trivial. According to this estimate, the kitchen counter in your fancy home is a bigger threat to your health. Yeah, basically; until they start labeling lumps of granite as "danger, radioactive" museums aren't going to do a damn thing about some dust that happens to be on a pressure suit!



(And now to repack...I really didn't want to dig for that book but I finally had to. What's the use of owning it if I don't use it every now and then?)

Offline Luke Pemberton

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Re: Radiation
« Reply #912 on: April 03, 2018, 01:44:56 PM »
I am like a proud father.  You have grown so much in the last 3 days.  Now that is a logarithmic graph.  Good job.

So where the dose from GCR lie, above or below the 0.22 mGr day-1 line?
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

I can calculate the motion of heavenly bodies, but not the madness of people – Sir Isaac Newton.

A polar orbit would also bypass the SAA - Tim Finch

Offline Jason Thompson

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Re: Radiation
« Reply #913 on: April 03, 2018, 01:45:55 PM »
Here you go Tim. The blue line is the data, the reddy-brown data is the threshold value of 0.22 mGr day-1.

What you can you say about most the blue data, other than SPE events? Plotted on a log graph for you. I've done nothing with the data.

I am like a proud father.  You have grown so much in the last 3 days.  Now that is a logarithmic graph.  Good job.

And yet yu have no comment on the obvious: that it shows huge parts of the data lie below what you insisted was the minimum....
"There's this idea that everyone's opinion is equally valid. My arse! Bloke who was a professor of dentistry for forty years does NOT have a debate with some eejit who removes his teeth with string and a door!"  - Dara O'Briain

Offline Rob48

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Re: Radiation
« Reply #914 on: April 03, 2018, 01:46:57 PM »

The axis is exponential and not logarithmic.  There is a subtle difference recognizable only by high school graduates.
Well, I'm a high-school and university graduate, and I can plainly see that the axis is logarithmic, as you can tell by the fact that the difference between the bottom two horizontal marks (10-4 and 10-3) is 0.0009 cGy/day, whereas the difference between the top two horizontal marks (104 and 103) is 9,000 cGy/day!

Specifically, because the vertical axis is logarithmic and the horizontal axis is linear, this is what is known as a semi-log plot.

I have never heard of an "exponential scale" as applied to a graph axis, and neither has the internet, other than as a synonym for logarithmic scale!