Elastic scattering in rotating thorium plate - Revision history

Burgjeff: /* Details */

2016-10-17T01:30:53Z

Details

Burgjeff: /* Details */

2016-10-17T01:30:41Z

Details

Burgjeff: /* Overview */

2016-10-17T01:29:01Z

Overview

Burgjeff: /* Details */

2016-10-17T01:25:21Z

Details

Burgjeff: /* Details */

2016-10-17T01:25:09Z

Details

Burgjeff: /* Details */

2016-10-17T01:24:37Z

Details

Burgjeff: /* Result */

2016-10-17T01:23:34Z

Result

Burgjeff at 01:23, 17 October 2016

2016-10-17T01:23:04Z

Burgjeff: /* Result */

2016-10-16T23:25:05Z

Result

Burgjeff: /* Result */

2016-10-16T23:22:16Z

Result

@@ Line 11: / Line 11: @@
 =Details=
-MCNP cannot directly simulate photons impinging on a rotating target, however, a rotating plane wave of photons is equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis producing a rotating pencil beam source. Fortunately, MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
+MCNP cannot directly simulate photons impinging on a rotating target, however, a rotating plane wave of photons is equivalent and can be done with MCNP. This was accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis producing a rotating pencil beam source. Fortunately, MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
 [[File:RotatingPhotonSourceFig.png|600px]]

@@ Line 11: / Line 11: @@
 =Details=
-MCNP cannot directly simulate photons impinging on a rotating target, however a rotating plane wave of photons is physically equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis producing a rotating pencil beam source. Fortunately, MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
+MCNP cannot directly simulate photons impinging on a rotating target, however, a rotating plane wave of photons is equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis producing a rotating pencil beam source. Fortunately, MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
 [[File:RotatingPhotonSourceFig.png|600px]]

@@ Line 3: / Line 3: @@
 =Overview=
-.5 MeV photons are generated uniformly on the curved face of a cylinder with a direction of travel inward and normal to the surface. Enclosed within the cylinder is a cuboid thorium target that is 4 cm high along the cylindrical axis, 0.5 mm thick, and 2 cm wide.
+.5 MeV photons are generated uniformly on the curved face of a cylinder with a direction of travel inward and normal to the surface, mimicking a rotating photon source. Enclosed within the cylinder is a cuboid thorium target that is 4 cm high along the cylindrical axis, 0.5 mm thick, and 2 cm wide.
 =Result=

@@ Line 11: / Line 11: @@
 =Details=
-MCNP cannot directly simulate photons impinging on a rotating target, however a rotating plane wave of photons is physically equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis producing a rotating pencil beam source. Fortunately MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
+MCNP cannot directly simulate photons impinging on a rotating target, however a rotating plane wave of photons is physically equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis producing a rotating pencil beam source. Fortunately, MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
 [[File:RotatingPhotonSourceFig.png|600px]]

@@ Line 11: / Line 11: @@
 =Details=
-MCNP cannot directly simulate photons impinging on a rotating target, however a rotating plane wave of photons is physically equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis. Fortunately MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
+MCNP cannot directly simulate photons impinging on a rotating target, however a rotating plane wave of photons is physically equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis producing a rotating pencil beam source. Fortunately MCNP allows the sampling of the angle between the surface normal and the direction of travel.  Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.
 [[File:RotatingPhotonSourceFig.png|600px]]

@@ Line 6: / Line 6: @@
 =Result=
-On average, photons see a target thickness of 0.72 mm and neutrons travel though 0.54 mm of thorium before escaping. 2.5% of fission neutrons underwent a scattering event, so statistically, '''95% of n-n pairs escape the target unmolested''', since <math> (1-0.025)^{2} \approx 0.95</math>.
+On average, photons see a target thickness of 0.72 mm and neutrons travel though 0.54 mm of thorium before escaping. 2.5% of fission neutrons underwent a scattering event, so statistically, '''95% of n-n pairs escape the target unmolested''', as shown by the following calculation:  <math> (1-0.025)^{2} \approx 0.95</math>.
 [[File:PhotonVSneutron.png|750px]]
 =Details=

← Older revision		Revision as of 01:23, 17 October 2016
Line 8:		Line 8:
	On average, photons see a target thickness of 0.72 mm and neutrons travel though 0.54 mm of thorium before escaping. 2.5% of fission neutrons underwent a scattering event, so statistically, '''95% of n-n pairs escape the target unmolested''', since <math> (1-0.025)^{2} \approx 0.95</math>.		On average, photons see a target thickness of 0.72 mm and neutrons travel though 0.54 mm of thorium before escaping. 2.5% of fission neutrons underwent a scattering event, so statistically, '''95% of n-n pairs escape the target unmolested''', since <math> (1-0.025)^{2} \approx 0.95</math>.

		+	[[File:PhotonVSneutron.png\|750px]]
		+
		+
		+	=Details=
		+	MCNP cannot directly simulate photons impinging on a rotating target, however a rotating plane wave of photons is physically equivalent and can be done with MCNP. It's accomplished by generating photons on the curved surface of a very large cylinder and sending them traveling inward towards the target. However, the photons shouldn't be given a direction of travel exactly along the cylindrical surface normal as this would not be like a rotating plane wave, since photon paths would always intersect with the symmetry axis. Fortunately MCNP allows the sampling of the angle between the surface normal and the direction of travel. Sampling this angle uniformly in a very small range centered around zero will produce a very good approximation of a plane wave, as long as the cylindrical surface is far from the target. Statistically, this is an infinite number of cone sources like the single one shown below, uniformly distributed over a cylindrical surface.

		+	[[File:RotatingPhotonSourceFig.png\|600px]]

−	~~[[File:PhotonVSneutron.png\|750px]]~~

	[[MCNP simulations \| go back]]		[[MCNP simulations \| go back]]

← Older revision		Revision as of 23:25, 16 October 2016
Line 6:		Line 6:

	=Result=		=Result=
−	On average, photons see a target thickness of 0.72 mm and neutrons travel though 0.54 mm of thorium before escaping. 2.5% of fission neutrons underwent a scattering event, so statistically, 95% of n-n pairs escape the target unmolested, since <math> (1-0.025)^{2} \approx 0.95</math>.	+	On average, photons see a target thickness of 0.72 mm and neutrons travel though 0.54 mm of thorium before escaping. 2.5% of fission neutrons underwent a scattering event, so statistically, '''95% of n-n pairs escape the target unmolested''', since <math> (1-0.025)^{2} \approx 0.95</math>.

@@ Line 7: / Line 7: @@
 =Result=
 On average, photons see a target thickness of 0.72 mm and neutrons travel though 0.54 mm of thorium before escaping. 2.5% of fission neutrons underwent a scattering event, so statistically, 95% of n-n pairs escape the target unmolested, since <math> (1-0.025)^{2} \approx 0.95</math>.
 [[File:PhotonVSneutron.png|750px]]
 [[MCNP simulations | go back]]