Ask the Scholar
Page 20 of 22
I can add historical knowledge about this page.
Page image
OCR
NO
DETECTION OF THORIUM EMANATION (THORON) IN EXPIRED AIR: In testing the expired
thoron was present. The total gamma ray activity represented
air from Subject O, it was established definitely that about 4
Hf 2 Mg.
With
expired air in the 3 liter ionization chamber of the Lind instrument, the initial
value of the ionization current observed was actually 30 times greater than the our-
rent the radon in the air of B
produced by present expired Subject bearing
radium. Are these experimental results in accord with theoretical expectations?
An approximate analysis of one concrete case will answer the question fully. Let us
consider a subject bearing 4 microgrems of mesothorium expressed as radium equivalent
and measured by the gamma ray method of evaluating specimens of mesothorium. Let
us arbitrarily assume that the mesothorium present has aged two to three years.
We
may then take, as a first approximation, (1) for the number of alpha particles expelled
from the thoron present per gram of mesothorium, a value one-half of 3.6 X 1010. ,
the
number of alpha particles expelled per second per curie of radon.
The number of
it
atoms of thoron continuously produced equalling as does, the number of alpha particles
expelled second by the thoron by 4
per disintegrating, M q mesothorium will then be
given by, -
X 3.6 X 1010 X 4 X 10-6 = 7.2 X 104
During 20 seconds, the time required to expire 3 liters of air, the number of atoms
of thoron present in the ionization chamber will be at best,
20 X 7.2 X 104 = 14.4 X 105.
But in the experimental part of
this paper we have shown that for radon not more than 5 per cent of the emanation
produced finds its way into the expired air. Assuming that the emanating power of
thorium
the parent of thoron is the same as its isotope radium, the parent of
radon, it follows that the actual number of atoms of thoron which will be carried into
4
the ionization chamber with the expired air lies in the neighborhood of 7 X 10 . Of
this number 1.28 per cent are transformed per second, which in this example will be
7 X 104 800.28 = 90
out
l. Of. Schlundt, Mesothorium Tech. Paper, 265, United States Bureau of Mines, p. 52.
Page data
- Page
- 20
- Source index
- 0
- Type
- photo
- Media ID
- c2fec760b7d1069e
- Size
- unknown
Document data
- ID
- 75730982
- Core
- doc
- Type
- document
DTO data
{
"id": "75730982",
"sourceUrl": "https://catalog.archives.gov/id/75730982",
"contentType": "document",
"title": "Report, no date",
"citationUrl": "https://catalog.archives.gov/id/75730982",
"collections": [
"Safety Light Collection",
"Records Related to Radium Dial Painters"
],
"iiifBase": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
"thumbnailUrl": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
"largeImageUrl": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
"imageCount": 22,
"hasImages": true,
"source": "import",
"hasTranscription": false
}
Context sent to Scholar
Document identity
{
"localId": "75730982",
"label": "Report, no date",
"core": "doc",
"dtoType": "document",
"citationUrl": "https://catalog.archives.gov/id/75730982"
}
Document source metadata
{
"id": "75730982",
"sourceUrl": "https://catalog.archives.gov/id/75730982",
"contentType": "document",
"title": "Report, no date",
"citationUrl": "https://catalog.archives.gov/id/75730982",
"collections": [
"Safety Light Collection",
"Records Related to Radium Dial Painters"
],
"iiifBase": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
"thumbnailUrl": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
"largeImageUrl": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_01.jpg",
"imageCount": 22,
"hasImages": true,
"source": "import",
"hasTranscription": false
}
Document source extras
{
"url": "https://catalog.archives.gov/id/75730982",
"naId": 75730982,
"levelOfDescription": "fileUnit",
"recordType": "description",
"ocrSource": "nara-archive"
}
Page context
{
"seq": 20,
"pageIndex": 0,
"type": "photo",
"url": "https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/SLC/Radium/SLC_0003761_Page_20.jpg",
"mediaId": "c2fec760b7d1069e",
"ocrText": "NO\nDETECTION OF THORIUM EMANATION (THORON) IN EXPIRED AIR: In testing the expired\nthoron was present. The total gamma ray activity represented\nair from Subject O, it was established definitely that about 4\nHf 2 Mg.\nWith\nexpired air in the 3 liter ionization chamber of the Lind instrument, the initial\nvalue of the ionization current observed was actually 30 times greater than the our-\nrent the radon in the air of B\nproduced by present expired Subject bearing\nradium. Are these experimental results in accord with theoretical expectations?\nAn approximate analysis of one concrete case will answer the question fully. Let us\nconsider a subject bearing 4 microgrems of mesothorium expressed as radium equivalent\nand measured by the gamma ray method of evaluating specimens of mesothorium. Let\nus arbitrarily assume that the mesothorium present has aged two to three years.\nWe\nmay then take, as a first approximation, (1) for the number of alpha particles expelled\nfrom the thoron present per gram of mesothorium, a value one-half of 3.6 X 1010. ,\nthe\nnumber of alpha particles expelled per second per curie of radon.\nThe number of\nit\natoms of thoron continuously produced equalling as does, the number of alpha particles\nexpelled second by the thoron by 4\nper disintegrating, M q mesothorium will then be\ngiven by, -\nX 3.6 X 1010 X 4 X 10-6 = 7.2 X 104\nDuring 20 seconds, the time required to expire 3 liters of air, the number of atoms\nof thoron present in the ionization chamber will be at best,\n20 X 7.2 X 104 = 14.4 X 105.\nBut in the experimental part of\nthis paper we have shown that for radon not more than 5 per cent of the emanation\nproduced finds its way into the expired air. Assuming that the emanating power of\nthorium\nthe parent of thoron is the same as its isotope radium, the parent of\nradon, it follows that the actual number of atoms of thoron which will be carried into\n4\nthe ionization chamber with the expired air lies in the neighborhood of 7 X 10 . Of\nthis number 1.28 per cent are transformed per second, which in this example will be\n7 X 104 800.28 = 90\nout\nl. Of. Schlundt, Mesothorium Tech. Paper, 265, United States Bureau of Mines, p. 52."
}