Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.physics > #588898 > unrolled thread

Basic Terms

Back to article view | Back to sci.physics

Contents

  Basic Terms Sergio <invalid@invalid.com> - 2016-07-12 09:49 -0500
    Re: Basic Terms noTthaTguY <abu.kuanysh05@gmail.com> - 2016-07-12 11:40 -0700
    Basic Terms john <johnsefton288@gmail.com> - 2016-07-12 11:59 -0700
      Re: Basic Terms Odd Bodkin <bodkinodd@gmail.com> - 2016-07-14 10:03 -0500
        Re: Basic Terms Poutnik <poutnik4nntp@gmail.com> - 2016-07-14 21:26 +0200
          Re: Basic Terms Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-07-17 15:55 +0200
        erm noTthaTguY <abu.kuanysh05@gmail.com> - 2016-07-14 13:13 -0700
    Re: Basic Terms xxein1@att.net - 2016-07-17 12:24 -0700

#588898 — Basic Terms

Basic Terms


Radiation

Radiation is energy in transit in the form of high speed particles and 
electromagnetic waves. We encounter electromagnetic waves every day. 
They make up our visible light, radio and television waves, ultra violet 
(UV), and microwaves with a spectrum of energies. These examples of 
electromagnetic waves do not cause ionizations of atoms because they do 
not carry enough energy to separate molecules or remove electrons from 
atoms.


Ionizing radiation

Ionizing radiation is radiation with enough energy so that during an 
interaction with an atom, it can remove tightly bound electrons from 
their orbits, causing the atom to become charged or ionized. Examples 
are gamma rays and neutrons. Radiation is measured in many ways, and 
commonly expressed in units of RAD.


Non-ionizing radiation

Non-ionizing radiation is radiation without enough energy to remove 
tightly bound electrons from their orbits around atoms. Examples are 
microwaves and visible light.


Health Physics

Health Physics is an interdisciplinary science and its application, for 
the radiation protection of humans and the environment. Health Physics 
combines the elements of physics, biology, chemistry, statistics and 
electronic instrumentation to provide information that can be used to 
protect individuals from the effects of radiation.


Radioactivity

Radioactivity is the spontaneous transformation of an unstable atom and 
often results in the emission of radiation. This process is referred to 
as a transformation, a decay or a disintegration of an atom.


Radioactive Material

Radioactive Material is any material that contains radioactive atoms.


Radioactive Contamination

Radioactive contamination is radioactive material distributed over some 
area, equipment or person. It tends to be unwanted in the location where 
it is, and has to be cleaned up or decontaminated.


Dose

In a general sense, dose is a measure of the amount of energy from an 
ionizing radiation deposited in a mass of some material. Dose is 
affected by the TYPE of radiation, the amount of radiation and the 
physical properties of the material itself. Specifically, we can talk 
about absorbed dose in tissue, or a material like silicon. Other common 
doses are the effective and equivalent doses, which are adjusted to 
allow the comparison of different tissues or types of radiation. 
Absorbed doses are normally measured in units of Gray (RAD), and 
effective and equivalent doses in Sievert (Rem).



Common Types of Radiation
Gamma Rays

Gamma rays are electromagnetic waves or photons emitted from the nucleus 
(center) of an atom.


Betas

A beta is a high speed particle, identical to an electron, that is 
emitted from the nucleus of an atom. It has an anti-matter counter part, 
sometimes called a Beta+, called a positron. A positron has the same 
mass and size as an electron but has a positive (+) charge versus the 
electron's negative (-) charge.


Alphas

An alpha is a particle emitted from the nucleus of an atom, that 
contains two protons and two neutrons. It is identical to the nucleus of 
a Helium atom, without the electrons.


Neutrons

Neutrons are neutral particles that are normally contained in the 
nucleus of all atoms and may be removed by various interactions or 
processes like collision and fission.


X rays

X Rays are electromagnetic waves or photons not emitted from the 
nucleus, but normally emitted by energy changes in electrons. These 
energy changes are either in electron orbital shells that surround an 
atom or in the process of slowing down such as in an X-ray machine.



Common Units - USA

These are the common units used in the United States in health physics.
Roentgen (R)

The Roentgen is a unit used to measure a quantity called exposure. This 
can only be used to describe an amount of gamma and X-rays, and only in 
air. One Roentgen is equal depositing to 2.58 x 10-4 coulombs per kg of 
dry air. It is a measure of the ionizations of the molecules in a mass 
of air. The main advantage of this unit is that it is easy to measure 
directly, but it is limited because it is only for deposition in air, 
and only for gamma and x rays.
RAD (Radiation Absorbed Dose)

The RAD is a unit used to measure a quantity called absorbed dose. This 
relates to the amount of energy actually absorbed in some material, and 
is used for any of radiation and any material. One RAD is defined as the 
absorption of 100 ergs per gram of material. The unit RAD can be used 
for any of radiation, but it does not describe the biological effects of 
the different radiations.
REM (Roentgen Equivalent Man)

The rem is a unit used to derive a quantity called equivalent dose. This 
relates the absorbed dose in human tissue to the effective biological 
damage of the radiation. Not all radiation has the same biological 
effect, even for the same amount of absorbed dose. Equivalent dose is 
often expressed in terms of thousandths of a rem, or millirem. To 
determine equivalent dose (rem), you multiply absorbed dose (RAD) by a 
quality factor (Q) that is unique to the of incident radiation.
Curie (Ci)

The curie is a unit used to measure a radioactivity. One curie is the 
amount of radioactivity in one gram of the element first discovered by 
Madame Curie, Radium. It is also the quantity of a radioactive material 
that will have 37,000,000,000 transformations in one second. Often 
radioactivity is expressed in smaller units like: thousandths (mCi), one 
millionths (uCi) or even billionths (nCi) of a curie. The relationship 
between Becquerel and curie is: 3.7 x 1010 Bq in one curie.
Common Units - SI - International Standard

Note: These are the common units used throughout the world in health 
physics.
Gray (Gy)

The gray is a unit used to measure a quantity called absorbed dose. This 
relates to the amount of energy actually absorbed in some material, and 
is used for any of radiation and any material. One gray is equal to one 
joule of energy deposited in one kg of a material. The unit gray can be 
used for any of radiation, but it does not describe the biological 
effects of the different radiations. Absorbed dose is often expressed in 
terms of hundredths of a gray, or centi-grays. One gray is equivalent to 
100 RAD.
Sievert (Sv)

The Sievert is a unit used to derive a quantity called equivalent dose. 
This relates the absorbed dose in human tissue to the effective 
biological damage of the radiation. Not all radiation has the same 
biological effect, even for the same amount of absorbed dose. Equivalent 
dose is often expressed in terms of millionths of a Sievert, or 
micro-Sievert. To determine equivalent dose (Sv), you multiply absorbed 
dose (Gy) by a quality factor (Q) that is unique to the of incident 
radiation. One Sievert is equivalent to 100 rem.
Becquerel (Bq)

The Becquerel is a unit used to measure a radioactivity. One Becquerel 
is that quantity of a radioactive material that will have 1 
transformation in one second. Often radioactivity is expressed in larger 
units like: thousands (kBq), millions (MBq) or even billions (GBq) of a 
Becquerel. As a result of having one Becquerel being equal to one 
transformation per second, there are 3.7 x 1010 Bq in one curie.



SI Prefixes

Many units are broken down into smaller units or expressed as multiples, 
using standard metric prefixes. As examples, a kilobecquerel (kBq) is 
1000 Becquerel, a millirad (mrad) is 10-3 RAD, a microrem (�rem) is 10-6 
rem, a nanogram is 10-9 grams, and a picocurie is a 10-12 curies.


SI Prefixes
Factor 	Prefix 	Symbols 	  	Factor 	Prefix 	Symbols
1018 	exa 	E 	  	10-1 	deci 	d
1015 	peta 	P 	  	10-2 	centi 	c
1012 	tera 	T 	  	10-3 	milli 	m
109 	giga 	G 	  	10-6 	micro 	�
106 	mega 	M 	  	10-9 	nano 	n
103 	kilo 	k 	  	10-12 	pico 	p
102 	hecto 	h 	  	10-15 	femto 	f
101 	deka 	da 	  	10-18 	atto 	a



Terms Related to Radiation Dose


Chronic dose

A chronic dose means a person received a radiation dose over a long 
period of time.
Acute dose

An acute dose means a person received a radiation dose over a short 
period of time.


Somatic effects

Somatic effects are effects from some agent, like radiation that are 
seen in the individual who receives the agent.


Genetic effects

Genetic effects are effects from some agent, that are seen in the 
offspring of the individual who received the agent. The agent must be 
encountered pre-conception.


Teratogenic effects

Teratogenic effects are effects from some agent, that are seen in the 
offspring of the individual who received the agent. The agent must be 
encountered during the gestation period.


Stochastic effects

Stochastic effects are effects that occur on a random basis with its 
effect being independent of the size of dose. The effect typically has 
no threshold and is based on probabilities, with the chances of seeing 
the effect increasing with dose. Cancer is thought to be a stochastic 
effect.


Non-stochastic effect

Non-stochastic effects are effects that can be related directly to the 
dose received. The effect is more severe with a higher dose, i.e., the 
burn gets worse as dose increases. It typically has a threshold, below 
which the effect will not occur. A skin burn from radiation is a 
non-stochastic effect.

[toc] | [next] | [standalone]

#588923

also there is a word, hormesis;
you could relate it to teratogenesis e.g

> Somatic effects are effects from some agent, like radiation that are 
> seen in the individual who receives the agent.
> 
> 
> Genetic effects
> 
> Genetic effects are effects from some agent, that are seen in the 
> offspring of the individual who received the agent. The agent must be 
> encountered pre-conception.
> 
> 
> Teratogenic effects
> 
> Teratogenic effects are effects from some agent, that are seen in the 
> offspring of the individual who received the agent. The agent must be 
> encountered during the gestation period.
> 
> 
> Stochastic effects
> 
> Stochastic effects are effects that occur on a random basis with its 
> effect being independent of the size of dose. The effect typically has 
> no threshold and is based on probabilities, with the chances of seeing 
> the effect increasing with dose. Cancer is thought to be a stochastic 
> effect.
> 
> 
> Non-stochastic effect
> 
> Non-stochastic effects are effects that can be related directly to the 
> dose received. The effect is more severe with a higher dose, i.e., the 
> burn gets worse as dose increases. It typically has a threshold, below 
> which the effect will not occur. A skin burn from radiation is a 
> non-stochastic effect.

[toc] | [prev] | [next] | [standalone]

#588929

"A beta is a high speed particle, identical to an electron, that is 
emitted from the nucleus of an atom. It has an anti-matter counter part, 
sometimes called a Beta+, called a positron. A positron has the same 
mass and size as an electron but has a positive (+) charge versus the 
electron's negative (-) charge. "
This chimes with
my latest conclusion
that a "down electron" is actually
a positron installed upside down

[toc] | [prev] | [next] | [standalone]

#589229

On 7/12/2016 1:59 PM, john wrote:
>
>
> "A beta is a high speed particle, identical to an electron, that is
> emitted from the nucleus of an atom. It has an anti-matter counter part,
> sometimes called a Beta+, called a positron. A positron has the same
> mass and size as an electron but has a positive (+) charge versus the
> electron's negative (-) charge. "
> This chimes with
> my latest conclusion
> that a "down electron" is actually
> a positron installed upside down
>

A spin-down electron has negative (-) charge, unlike a positron.

A beam of unpolarized electrons can be separated with a magnet into 
spin-up and spin-down electrons, without any sign of annihilation. If 
you mixed any set of electrons with positrons, you would see a bunch of 
1.022 MeV gamma rays, sign of annihilation.

Photons recoiling from a nucleus will generate an electron-positron pair 
but NEVER into a spin-up-electron + spin-down-electron pair. The latter 
would violate conservation of electric charge.

There are about 980 other differences between spin-down electrons and 
positrons, John. Despite the one thing that smacks of some resemblance 
between the two for you. Sorta like cows and pigs -- "Hey they both have 
four legs and generate meat!"



-- 
Odd Bodkin --- maker of fine toys, tools, tables

[toc] | [prev] | [next] | [standalone]

#589287

Dne 14/07/2016 v 17:03 Odd Bodkin napsal(a):

> 
> ....   If
> you mixed any set of electrons with positrons, you would see a bunch of 
> 1.022 MeV gamma rays, sign of annihilation.
> 
Rather 2-5 photons of total energy  1.022 MeV per the pair.

-- 
Poutnik ( The Pilgrim, Der Wanderer )
Knowledge makes great men humble, but small men arrogant.

[toc] | [prev] | [next] | [standalone]

#589638

Poutnik wrote:

> Dne 14/07/2016 v 17:03 Odd Bodkin napsal(a):
>> ....   If
>> you mixed any set of electrons with positrons, you would see a bunch of
>> 1.022 MeV gamma rays, sign of annihilation.
>
> Rather 2-5 photons

Or more.

> of total energy  1.022 MeV per the pair.

In the collison frame only.

-- 
PointedEars

Twitter: @PointedEars2
Please do not cc me. / Bitte keine Kopien per E-Mail. 

[toc] | [prev] | [next] | [standalone]

#589291 — erm

I see the classical notion of recoil,
apparently applied to the pair of trons;
is this supposed to have been "the direction of the lightwave?

> Photons recoiling from a nucleus will generate an electron-positron pair 
> but NEVER into a spin-up-electron + spin-down-electron pair. The latter 
> would violate conservation of electric charge.
> 
> There are about 980 other differences between spin-down electrons and 
> positrons, John. Despite the one thing that smacks of some resemblance 
> between the two for you. Sorta like cows and pigs -- "Hey they both have 
> four legs and generate meat!"
> 
> 
> 
> -- 
> Odd Bodkin --- maker of fine toys, tools, tables

[toc] | [prev] | [next] | [standalone]

#589661

On Tuesday, July 12, 2016 at 10:49:42 AM UTC-4, Sergio wrote:
> Basic Terms
> 

xxein:  I got this old box of dark energy here.  How do I play with it?

[toc] | [prev] | [standalone]

Back to top | Article view | sci.physics

csiph-web