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HRRL Electron OSA

2013-12-17T23:27:00Z

Swanjase:

[http://wiki.iac.isu.edu/index.php/HRRL_OSA_Docs Go Back]

Operational Safety Assessment

Low Dose Detector Testing Using the High Repetion Rate Linac (HRRL) at
the Particle Beam Laboratory
10/26/2008

1. Accelerator Description and Test Purpose

This document outlines a procedure to determine if a low current of 3 MeV electrons from the High Repetion Rate Linac (HRRL) may be used to test detectors in the HRRL experimental cell. The HRRL is an e-linac located in the basement of the physics building which is capable of 25 ns to 1 usec long beam pulses up to 80 mA peak currents at a repetition rate of 2 kHz. The beam energy can range between 3 and 15 MeV. The HRRL has previously been used to deliver a bremsstrahlung beam to an adjacent experimental cell for several experiments. We would like to compare a measurement of the radiation field generated when operating the HRRL with our Monte Carlo calculations to determine if the HRRL may be used to source a 25 ns wide pulse of 3 MeV electrons.

The goal of this test is measure the dose in public areas around the HRRL experimental cell when the HRRL is configured to deliver a single electron per pulse to the HRRL experimental cell. A MCNPX and GEANT4 Monte Carlo both estimate that a 25 nsec long peak beam current of 2 mA would generate less than 2 mrad/hr above a 6" concrete ceiling assumed to exist above the HRRL experimental cell. ISU's dose limits for the general public are currently set for 100 mrem/year according to the Radiation Safety Training Guide (Rev 08/07).
Our goal is to inject only one electron per pulse into the HRRL experimental Cell, a current several order of manginute less than 2 mA even at the maximum HRRL rep rate.

A small apperature collimator will be used to reduce the current into the HRRL experimental cell from its maximum current of 80 mA to less than 2 mA peak current inside the HRRL experimental cell. The beam spot size after the 90 degree bend has been observed to be a 2 cm long oval that is about 1 cm wide and does not exceed this size due to the intrinsic collimation of the dipole bending magnet. A 2" x 4" x 8" Aluminum block collimator with a 2 mm diameter hole will be placed near the HRRL experimental wall in order to reduce the current. The current would be reduced by at least a factor of 30 if there were no beam divergence thereby reducing the peak beam current to 2.5 mA resulting in a dose of about 2 mrad/hr above the HRRL ceiling cell if there were no beam loss.

[[Image:Electrons_hit_Phos_screen.jpg | 100 px]][[Image:Electrons_hit_Phos_screen_2.jpg | 100 px]]

The HRRL ceiling dose is expected to be lower than 2 mrad/hr due to the beam divergence and transport loss into the HRRL experimental cell using the collimation described above. The collimator will also be used to monitor the peak current on the accelerator side. The Aluminum collimator with the 1 mm diameter hole will have an aluminum shutter placed in front of it to allow the accelerator operators to tune the electron beam and prevent the transport of electrons into the HRRL experimental cell. The shutter can be remotely opened after establishing stable accelerator operations and maximum beam spot size. A FC will be placed on the HRRL experimental cell side of the wall that is able to measure peak currents down to 2mA and can be used as a fast accelerator shutdown interlock to prevent current in the HRRL experimental cell that would exceed a dose 2 mrad/hr in public areas near the cell. Measurements from this test will be used to define the safety envelope and associated HRRL operational parameters.

2. Safety

The initial beam injection test will be monitored by the ISU Technical Safety Office (TSO) to establish safe operations (SO). Upon the establishment of SO the TSO will provide monitoring as determined necessary based on initial operations. To address the operational safety needs shielding, interlocks, warning lights, audible signals, manual scram buttons, radiation survey instruments, and in the shielding properties of the building will be utilized. A diagram is attached.

1. Interlocks. The HRRL power supply is interlocked to the current building interlock system such that the access to the operational cell area will break the interlock chain disabling the accelerator. After the interlocks are set and before the accelerator will operate an audible and visual warning will be activated. Interlock characteristics are as per the standard IAC interlock system including, lights, keys, scrams, inspection buttons, etc., as follows:

a. Lights. Rotating beacons, yellow for interlocks set, red for beam on.

b. Audible Alarms. After interlocks are set a 30-second audible alarm is sounded. Only after the cessation of the audible alarm will the accelerator operate.

c. Keys. A key is required to set interlocks and a separate key must be set to allow the enable button upon the accelerator computer touch screen to actuate.

d. Scrams. Scram buttons are collocated with inspection buttons. Depressing a scram will deactivate the interlocks shutting off the accelerator and require the interlock arming procedure to be repeated before resuming operation.

e. Inspection Buttons. These buttons must be depressed within two (2) minutes of final interlock setting.

f. Area Monitors. When operating limits are established area monitors will be interlocked to the accelerator such that at preset limit the accelerator will be caused to trip off.

g. Area Monitor #2. This is an independent monitor that will indicate dose rate at the cell door.

2. Survey instruments. No entrance into the cell radiation area will be allowed after tests without the presence of the operator or operator designee with out the Power Supply Key, and a TSO-approved survey meter.

3. Operators. Only IAC professional staff will operate the HRRL during the tests.

4. Radiation surveys. Surveys of the 1st floor areas and other potential hot spots will be conducted by TSO personnel and/or TSO designees.

5. Radiation Measurements to be made. TSO or designee will make radiation field measurements.

a. Left East Wall Beowulf room

b. Corridor and Control Area

c. Upstairs in W end of Physics Offices

d. Outside on W end of addition

e. In the vicinity of the klystron

[http://wiki.iac.isu.edu/index.php/HRRL_OSA_Docs Go Back]

HRRL Electron OSA

2013-12-17T23:26:26Z

Swanjase:

[http://wiki.iac.isu.edu/index.php/HRRL_OSA_Docs Go Back]

Operational Safety Assessment

Low Dose Detector Testing Using the High Repetion Rate Linac (HRRL) at
the Particle Beam Laboratory
10/26/2008

1. Accelerator Description and Test Purpose

This document outlines a procedure to determine if a low current of 3 MeV electrons from the High Repetion Rate Linac (HRRL) may be used to test detectors in the HRRL experimental cell. The HRRL is an e-linac located in the basement of the physics building which is capable of 25 ns to 1 usec long beam pulses up to 80 mA peak currents at a repetition rate of 2 kHz. The beam energy can range between 3 and 15 MeV. The HRRL has previously been used to deliver a bremsstrahlung beam to an adjacent experimental cell for several experiments. We would like to compare a measurement of the radiation field generated when operating the HRRL with our Monte Carlo calculations to determine if the HRRL may be used to source a 25 ns wide pulse of 3 MeV electrons.

The goal of this test is measure the dose in public areas around the HRRL experimental cell when the HRRL is configured to deliver a single electron per pulse to the HRRL experimental cell. A MCNPX and GEANT4 Monte Carlo both estimate that a 25 nsec long peak beam current of 2 mA would generate less than 2 mrad/hr above a 6" concrete ceiling assumed to exist above the HRRL experimental cell. ISU's dose limits for the general public are currently set for 100 mrem/year according to the Radiation Safety Training Guide (Rev 08/07).
Our goal is to inject only one electron per pulse into the HRRL experimental Cell, a current several order of manginute less than 2 mA even at the maximum HRRL rep rate.

A small apperature collimator will be used to reduce the current into the HRRL experimental cell from its maximum current of 80 mA to less than 2 mA peak current inside the HRRL experimental cell. The beam spot size after the 90 degree bend has been observed to be a 2 cm long oval that is about 1 cm wide and does not exceed this size due to the intrinsic collimation of the dipole bending magnet. A 2" x 4" x 8" Aluminum block collimator with a 2 mm diameter hole will be placed near the HRRL experimental wall in order to reduce the current. The current would be reduced by at least a factor of 30 if there were no beam divergence thereby reducing the peak beam current to 2.5 mA resulting in a dose of about 2 mrad/hr above the HRRL ceiling cell if there were no beam loss.

[[Image:Electrons_hit_Phos_screen.jpg | 100.px]][[Image:Electrons_hit_Phos_screen_2.jpg | 100.px]]

The HRRL ceiling dose is expected to be lower than 2 mrad/hr due to the beam divergence and transport loss into the HRRL experimental cell using the collimation described above. The collimator will also be used to monitor the peak current on the accelerator side. The Aluminum collimator with the 1 mm diameter hole will have an aluminum shutter placed in front of it to allow the accelerator operators to tune the electron beam and prevent the transport of electrons into the HRRL experimental cell. The shutter can be remotely opened after establishing stable accelerator operations and maximum beam spot size. A FC will be placed on the HRRL experimental cell side of the wall that is able to measure peak currents down to 2mA and can be used as a fast accelerator shutdown interlock to prevent current in the HRRL experimental cell that would exceed a dose 2 mrad/hr in public areas near the cell. Measurements from this test will be used to define the safety envelope and associated HRRL operational parameters.

2. Safety

The initial beam injection test will be monitored by the ISU Technical Safety Office (TSO) to establish safe operations (SO). Upon the establishment of SO the TSO will provide monitoring as determined necessary based on initial operations. To address the operational safety needs shielding, interlocks, warning lights, audible signals, manual scram buttons, radiation survey instruments, and in the shielding properties of the building will be utilized. A diagram is attached.

1. Interlocks. The HRRL power supply is interlocked to the current building interlock system such that the access to the operational cell area will break the interlock chain disabling the accelerator. After the interlocks are set and before the accelerator will operate an audible and visual warning will be activated. Interlock characteristics are as per the standard IAC interlock system including, lights, keys, scrams, inspection buttons, etc., as follows:

a. Lights. Rotating beacons, yellow for interlocks set, red for beam on.

b. Audible Alarms. After interlocks are set a 30-second audible alarm is sounded. Only after the cessation of the audible alarm will the accelerator operate.

c. Keys. A key is required to set interlocks and a separate key must be set to allow the enable button upon the accelerator computer touch screen to actuate.

d. Scrams. Scram buttons are collocated with inspection buttons. Depressing a scram will deactivate the interlocks shutting off the accelerator and require the interlock arming procedure to be repeated before resuming operation.

e. Inspection Buttons. These buttons must be depressed within two (2) minutes of final interlock setting.

f. Area Monitors. When operating limits are established area monitors will be interlocked to the accelerator such that at preset limit the accelerator will be caused to trip off.

g. Area Monitor #2. This is an independent monitor that will indicate dose rate at the cell door.

2. Survey instruments. No entrance into the cell radiation area will be allowed after tests without the presence of the operator or operator designee with out the Power Supply Key, and a TSO-approved survey meter.

3. Operators. Only IAC professional staff will operate the HRRL during the tests.

4. Radiation surveys. Surveys of the 1st floor areas and other potential hot spots will be conducted by TSO personnel and/or TSO designees.

5. Radiation Measurements to be made. TSO or designee will make radiation field measurements.

a. Left East Wall Beowulf room

b. Corridor and Control Area

c. Upstairs in W end of Physics Offices

d. Outside on W end of addition

e. In the vicinity of the klystron

[http://wiki.iac.isu.edu/index.php/HRRL_OSA_Docs Go Back]

Neutron Corr

2012-10-02T20:58:50Z

Swanjase:

[https://wiki.iac.isu.edu/index.php/HRRL Go Back]
=8/13/2012=
==First Results==
[[File:G1L3966.png | 600 px]]
[[File:G1L3967.png | 600 px]]

=8/14/2012=
==Gun/RF Tests==
[[File:betterbeamtest.jpg | 600 px]]

=8/15/2012=
==Neutron Detector Layout==
[[File:HRRL_LANDLO_8_15.jpg | 800px]]

=8/16/2012=
==Neutron Detector Layout(morning)==
[[File:HRRL_LANDLO_8_16_am.jpg | 800px]]
==Neutron Detector Layout(afternoon)==
[[File:HRRL_LANDLO_8_16_pm.jpg | 800px]]

=8/17/2012 - 8/24/2012=
==Neutron Detector Layout==
[[File:HRRL_LANDLO_8_20.jpg | 800px]]

=August 2012 HRRL Data Analysis=

The detector measurements used for this data analysis are illustrated in the schematic below:

[[File:2ndetectormeas.jpeg | 800 px]]

Using the index of refraction Oleksiy found:

[[File:Slope_data.png]]

When analyzing the data, all the runs in a particular day were added together for better statistics. First, the raw data was used to determine where the neutrons cut would need to be placed for each run (or each day of runs if they were able to be combined). Applying those neutron cuts to each TDC, coincidences were found. The TDC spectra of the detectors that detected these coincidences were then analyzed to determine the spot on the detectors where each neutron hit. Knowing the location of detection, the theta and phi angles between coincident neutrons were found.

==8/17==
Raw Data:

[[File:TDC8_17.png | 800 px]]

Coincidence Data:

[[File:phi 8_17.png | 800 px]]

[[File:theta 8_17.png | 800 px]]

==8/20==
Raw Data:

[[File:TDC8_20.png | 800 px]]

Coincidence Data:

[[File:phi8_20.png | 800 px]]

[[File:theta8_20.png | 800 px]]

==8/21==
Raw Data:

[[File:TDC8_21.png | 800 px]]

Here the multiple peak indicate that the timing in the beam was shifting, thus not allowing to combine. Each run of this day is plotted below.

===4143===
[[File:TDC8_21_4143.png | 800 px]]

===4144===
[[File:TDC8_21_4144.png | 800 px]]

===4145===
[[File:TDC8_21_4145.png | 800 px]]

===4146===
[[File:TDC8_21_4146.png | 800 px]]

==8/22==
Raw Data:

[[File:TDC8_22.png | 800 px]]

Coincidence Data:

[[File:phi8_22.png | 800 px]]

[[File:theta8_22.png | 800 px]]

==8/23==
Raw Data:

[[File:TDC_8_23.png | 800 px]]

Coincidence Data:

[[File:phi8_23.png | 800 px]]

[[File:theta8_23.png | 800 px]]

==8/24==
Raw Data:

[[File:TDC8_24.png | 800 px]]

Coincidence Data:

[[File:phi8_24.png | 800 px]]

[[File:theta8_24.png | 800 px]]

==8/17 - 8/20==
[[File:TDC8_17_20.png | 800 px]]

==8/17 - 8/21==
[[File:TDC8_17_21.png | 800 px]]

==8/17 - 8/22==
[[File:TDC8_17_22.png | 800 px]]

[https://wiki.iac.isu.edu/index.php/HRRL Go Back]

2-Neutron Correlation

2012-10-02T20:51:52Z

Swanjase: /* 8/21 */

=Pre-setup Calculations=
== Big Detector Solid Angle Calculations ==
[https://wiki.iac.isu.edu/index.php/Neutron_Corr Neutron Corr Home Page]
; MCNPX Simulation 
* 14 MeV neutron source, emitted isotropically (<math>4\pi</math>) 
* Detector placed 1m away from source 
[[File:mcnpxsetup.png | 500px]]

* face of the detector is 15.24cm x 76.2cm, and 3.6cm deep 
[[File:DetectorDimensions.png | 500px]]

The solid angle can be found from the number of particles hitting the detector as: 
<math>\Delta \Omega = 4\pi*\frac{hits}{hits + misses}</math>

; Results
* Out of 1E9 neutrons generated, 8618287 neutrons hit the detector
** <math>\Delta \Omega = 0.108 Sr</math>
*** if the detector is placed 70cm away from the source, <math>\Delta \Omega = 0.207 Sr</math>
*** if the detector is placed 65cm away from the source, <math>\Delta \Omega = 0.236 Sr</math>

* As a test to verify our results
** We change the detector size to 2cm by 2cm and used 1E9 neutrons again
** 32061 neutrons struck the detector
** <math>\Delta \Omega = 0.0004 Sr</math>

* And, as a second test to verify our results
** We change the detector size to 1cm by 1cm and used 1E9 neutrons again
** 7965 neutrons struck the detector
** <math>\Delta \Omega = 0.0001 Sr</math>

; Now, what neutron singles rate into the detector should correspond to 1 fission per pulse?
* If we have 1 fission per pulse and each fission emits on average 2.3 neutrons, we should expect 2.3 neutrons/pulse
* The number of neutrons hitting the detector per pulse is found as <math>2.3*\frac{\Delta \Omega}{4\pi}</math>
** @ 1 meter => 0.0198 neutrons hitting the detector per pulse
** @ 70 cm => 0.0379 neutrons hitting the detector per pulse
* Taking into account the efficiency of the detector <math>\epsilon_0</math>, the number detected per pulse can be found as <math>2.3*\frac{\Delta \Omega}{4\pi}*\epsilon_0</math>
** @ 1 meter from source => (<math>0.0198*\epsilon_0=0.0198*0.17=0.003</math>) neutrons detected per pulse
** @ 70 cm from source => (<math>0.0379*\epsilon_0=0.0379*0.17=0.006</math>) neutrons detected per pulse

==Neutron and Photon Flux Through Lead==

Using MCNPX, a simulation was done to determine how much of the neutrons and photons from the target will be blocked by various thickness of lead. With a monochromatic pencil beam of incident particles, the following results illustrate how much of the initial beam actually made it through the lead.

[[File:1MeV_Lead.jpg | 600px]]

[[File:5MeV_Lead.jpg | 600px]]

==Neutron and Photon Flux Through Concrete==

[[File:1MeV_Concrete.jpg | 600px]]

== Detector Cross-Talk ==

Using MCNPX, I am trying to simulated the cross-talk we could expect between the big detectors. I used a fission neutron energy spectrum given in MCNPX, shown below.

[[File:FissionNeutronEnergySpectrum.jpg | 800px]]

These neutrons are incident upon a plastic scintillator and I will look at the neutrons and photons coming out of the scintillator's sides perpendicular to the incident beam. The first case I will look at is where the detectors are placed with only polyethylene between them, as illustrated below.

[[File:OLead.png | 400px]]

This results in a neutron and photon energy spectrum as follows.

[[File:NeutronEnergySpectrum.jpg | 800px]]

[[File:PhotonEnergySpectrum.jpg | 800px]]

The next case I will look at is where we put a layer of lead between the polyethylene between the detectors, as shown in the schematic below.

[[File:DetectorSetupwLead.png | 400px]]

The results for this setup using 1 inch of lead between the detectors is as follows.

[[File:NeutronEnergySpectrumPb.jpg | 800px]]

[[File:PhotonEnergySpectrum1inPb.jpg | 800px]]

And, the results for this setup using 2 inches of lead between the detectors is as follows.

[[File:NeutronEnergySpectrum2Pb.jpg | 800px]]

[[File:PhotonEnergySpectrum2Pb.jpg | 800px]]

=August 2012 HRRL Data Analysis=

The detector measurements used for this data analysis are illustrated in the schematic below:

[[File:2ndetectormeas.jpeg | 800 px]]

Using the index of refraction Oleksiy found:

[[File:Slope_data.png]]

When analyzing the data, all the runs in a particular day were added together for better statistics. First, the raw data was used to determine where the neutrons cut would need to be placed for each run (or each day of runs if they were able to be combined). Applying those neutron cuts to each TDC, coincidences were found. The TDC spectra of the detectors that detected these coincidences were then analyzed to determine the spot on the detectors where each neutron hit. Knowing the location of detection, the theta and phi angles between coincident neutrons were found.

==8/17==
Raw Data:

[[File:TDC8_17.png | 800 px]]

Coincidence Data:

[[File:phi 8_17.png | 800 px]]

[[File:theta 8_17.png | 800 px]]

==8/20==
Raw Data:

[[File:TDC8_20.png | 800 px]]

Coincidence Data:

[[File:phi8_20.png | 800 px]]

[[File:theta8_20.png | 800 px]]

==8/21==
Raw Data:

[[File:TDC8_21.png | 800 px]]

Here the multiple peak indicate that the timing in the beam was shifting, thus not allowing to combine. Each run of this day is plotted below.

===4143===
[[File:TDC8_21_4143.png | 800 px]]

===4144===
[[File:TDC8_21_4144.png | 800 px]]

===4145===
[[File:TDC8_21_4145.png | 800 px]]

===4146===
[[File:TDC8_21_4146.png | 800 px]]

==8/22==
Raw Data:

[[File:TDC8_22.png | 800 px]]

Coincidence Data:

[[File:phi8_22.png | 800 px]]

[[File:theta8_22.png | 800 px]]

==8/23==
Raw Data:

[[File:TDC_8_23.png | 800 px]]

Coincidence Data:

[[File:phi8_23.png | 800 px]]

[[File:theta8_23.png | 800 px]]

==8/24==
Raw Data:

[[File:TDC8_24.png | 800 px]]

Coincidence Data:

[[File:phi8_24.png | 800 px]]

[[File:theta8_24.png | 800 px]]

==8/17 - 8/20==
[[File:TDC8_17_20.png | 800 px]]

==8/17 - 8/21==
[[File:TDC8_17_21.png | 800 px]]

==8/17 - 8/22==
[[File:TDC8_17_22.png | 800 px]]

[https://wiki.iac.isu.edu/index.php/User:Jasenswanson Go Back]

2012-10-02T20:06:21Z

Swanjase:

File:TDC8 24.png

2012-10-02T20:04:22Z

Swanjase:

2-Neutron Correlation

2012-10-02T20:03:50Z

Swanjase: /* 8/23 */

== Big Detector Solid Angle Calculations ==
[https://wiki.iac.isu.edu/index.php/Neutron_Corr Neutron Corr Home Page]
; MCNPX Simulation 
* 14 MeV neutron source, emitted isotropically (<math>4\pi</math>) 
* Detector placed 1m away from source 
[[File:mcnpxsetup.png | 500px]]

* face of the detector is 15.24cm x 76.2cm, and 3.6cm deep 
[[File:DetectorDimensions.png | 500px]]

The solid angle can be found from the number of particles hitting the detector as: 
<math>\Delta \Omega = 4\pi*\frac{hits}{hits + misses}</math>

; Results
* Out of 1E9 neutrons generated, 8618287 neutrons hit the detector
** <math>\Delta \Omega = 0.108 Sr</math>
*** if the detector is placed 70cm away from the source, <math>\Delta \Omega = 0.207 Sr</math>
*** if the detector is placed 65cm away from the source, <math>\Delta \Omega = 0.236 Sr</math>

* As a test to verify our results
** We change the detector size to 2cm by 2cm and used 1E9 neutrons again
** 32061 neutrons struck the detector
** <math>\Delta \Omega = 0.0004 Sr</math>

* And, as a second test to verify our results
** We change the detector size to 1cm by 1cm and used 1E9 neutrons again
** 7965 neutrons struck the detector
** <math>\Delta \Omega = 0.0001 Sr</math>

; Now, what neutron singles rate into the detector should correspond to 1 fission per pulse?
* If we have 1 fission per pulse and each fission emits on average 2.3 neutrons, we should expect 2.3 neutrons/pulse
* The number of neutrons hitting the detector per pulse is found as <math>2.3*\frac{\Delta \Omega}{4\pi}</math>
** @ 1 meter => 0.0198 neutrons hitting the detector per pulse
** @ 70 cm => 0.0379 neutrons hitting the detector per pulse
* Taking into account the efficiency of the detector <math>\epsilon_0</math>, the number detected per pulse can be found as <math>2.3*\frac{\Delta \Omega}{4\pi}*\epsilon_0</math>
** @ 1 meter from source => (<math>0.0198*\epsilon_0=0.0198*0.17=0.003</math>) neutrons detected per pulse
** @ 70 cm from source => (<math>0.0379*\epsilon_0=0.0379*0.17=0.006</math>) neutrons detected per pulse

==Neutron and Photon Flux Through Lead==

Using MCNPX, a simulation was done to determine how much of the neutrons and photons from the target will be blocked by various thickness of lead. With a monochromatic pencil beam of incident particles, the following results illustrate how much of the initial beam actually made it through the lead.

[[File:1MeV_Lead.jpg | 600px]]

[[File:5MeV_Lead.jpg | 600px]]

==Neutron and Photon Flux Through Concrete==

[[File:1MeV_Concrete.jpg | 600px]]

== Detector Cross-Talk ==

Using MCNPX, I am trying to simulated the cross-talk we could expect between the big detectors. I used a fission neutron energy spectrum given in MCNPX, shown below.

[[File:FissionNeutronEnergySpectrum.jpg | 800px]]

These neutrons are incident upon a plastic scintillator and I will look at the neutrons and photons coming out of the scintillator's sides perpendicular to the incident beam. The first case I will look at is where the detectors are placed with only polyethylene between them, as illustrated below.

[[File:OLead.png | 400px]]

This results in a neutron and photon energy spectrum as follows.

[[File:NeutronEnergySpectrum.jpg | 800px]]

[[File:PhotonEnergySpectrum.jpg | 800px]]

The next case I will look at is where we put a layer of lead between the polyethylene between the detectors, as shown in the schematic below.

[[File:DetectorSetupwLead.png | 400px]]

The results for this setup using 1 inch of lead between the detectors is as follows.

[[File:NeutronEnergySpectrumPb.jpg | 800px]]

[[File:PhotonEnergySpectrum1inPb.jpg | 800px]]

And, the results for this setup using 2 inches of lead between the detectors is as follows.

[[File:NeutronEnergySpectrum2Pb.jpg | 800px]]

[[File:PhotonEnergySpectrum2Pb.jpg | 800px]]

=Neutron Detector TDC Spectra Thick Uranium Target=

==8/17==
[[File:TDC8_17.png | 800 px]]

[[File:phi8_17.png | 800 px]]

[[File:theta8_17.png | 800 px]]

==8/20==
[[File:TDC8_20.png | 800 px]]

[[File:phi8_20.png | 800 px]]

[[File:theta8_20.png | 800 px]]

==8/21==
[[File:TDC8_21.png | 800 px]]

===4143===
[[File:TDC8_21_4143.png | 800 px]]

===4144===
[[File:TDC8_21_4144.png | 800 px]]

===4145===
[[File:TDC8_21_4145.png | 800 px]]

===4146===
[[File:TDC8_21_4146.png | 800 px]]

==8/22==
[[File:TDC8_22.png | 800 px]]

[[File:phi8_22.png | 800 px]]

[[File:theta8_22.png | 800 px]]

==8/23==
[[File:TDC_8_23.png | 800 px]]

[[File:phi8_23.png | 800 px]]

[[File:theta8_23.png | 800 px]]

==8/24==
[[File:TDC8_24.png | 800 px]]

[[File:phi8_24.png | 800 px]]

[[File:theta8_24.png | 800 px]]

==8/17 - 8/20==
[[File:TDC8_17_20.png | 800 px]]

==8/17 - 8/21==
[[File:TDC8_17_21.png | 800 px]]

==8/17 - 8/22==
[[File:TDC8_17_22.png | 800 px]]

[https://wiki.iac.isu.edu/index.php/User:Jasenswanson Go Back]

2-Neutron Correlation

2012-10-02T20:00:29Z

== Big Detector Solid Angle Calculations ==
[https://wiki.iac.isu.edu/index.php/Neutron_Corr Neutron Corr Home Page]
; MCNPX Simulation 
* 14 MeV neutron source, emitted isotropically (<math>4\pi</math>) 
* Detector placed 1m away from source 
[[File:mcnpxsetup.png | 500px]]

* face of the detector is 15.24cm x 76.2cm, and 3.6cm deep 
[[File:DetectorDimensions.png | 500px]]

The solid angle can be found from the number of particles hitting the detector as: 
<math>\Delta \Omega = 4\pi*\frac{hits}{hits + misses}</math>

; Results
* Out of 1E9 neutrons generated, 8618287 neutrons hit the detector
** <math>\Delta \Omega = 0.108 Sr</math>
*** if the detector is placed 70cm away from the source, <math>\Delta \Omega = 0.207 Sr</math>
*** if the detector is placed 65cm away from the source, <math>\Delta \Omega = 0.236 Sr</math>

* As a test to verify our results
** We change the detector size to 2cm by 2cm and used 1E9 neutrons again
** 32061 neutrons struck the detector
** <math>\Delta \Omega = 0.0004 Sr</math>

* And, as a second test to verify our results
** We change the detector size to 1cm by 1cm and used 1E9 neutrons again
** 7965 neutrons struck the detector
** <math>\Delta \Omega = 0.0001 Sr</math>

; Now, what neutron singles rate into the detector should correspond to 1 fission per pulse?
* If we have 1 fission per pulse and each fission emits on average 2.3 neutrons, we should expect 2.3 neutrons/pulse
* The number of neutrons hitting the detector per pulse is found as <math>2.3*\frac{\Delta \Omega}{4\pi}</math>
** @ 1 meter => 0.0198 neutrons hitting the detector per pulse
** @ 70 cm => 0.0379 neutrons hitting the detector per pulse
* Taking into account the efficiency of the detector <math>\epsilon_0</math>, the number detected per pulse can be found as <math>2.3*\frac{\Delta \Omega}{4\pi}*\epsilon_0</math>
** @ 1 meter from source => (<math>0.0198*\epsilon_0=0.0198*0.17=0.003</math>) neutrons detected per pulse
** @ 70 cm from source => (<math>0.0379*\epsilon_0=0.0379*0.17=0.006</math>) neutrons detected per pulse

==Neutron and Photon Flux Through Lead==

Using MCNPX, a simulation was done to determine how much of the neutrons and photons from the target will be blocked by various thickness of lead. With a monochromatic pencil beam of incident particles, the following results illustrate how much of the initial beam actually made it through the lead.

[[File:1MeV_Lead.jpg | 600px]]

[[File:5MeV_Lead.jpg | 600px]]

==Neutron and Photon Flux Through Concrete==

[[File:1MeV_Concrete.jpg | 600px]]

== Detector Cross-Talk ==

Using MCNPX, I am trying to simulated the cross-talk we could expect between the big detectors. I used a fission neutron energy spectrum given in MCNPX, shown below.

[[File:FissionNeutronEnergySpectrum.jpg | 800px]]

These neutrons are incident upon a plastic scintillator and I will look at the neutrons and photons coming out of the scintillator's sides perpendicular to the incident beam. The first case I will look at is where the detectors are placed with only polyethylene between them, as illustrated below.

[[File:OLead.png | 400px]]

This results in a neutron and photon energy spectrum as follows.

[[File:NeutronEnergySpectrum.jpg | 800px]]

[[File:PhotonEnergySpectrum.jpg | 800px]]

The next case I will look at is where we put a layer of lead between the polyethylene between the detectors, as shown in the schematic below.

[[File:DetectorSetupwLead.png | 400px]]

The results for this setup using 1 inch of lead between the detectors is as follows.

[[File:NeutronEnergySpectrumPb.jpg | 800px]]

[[File:PhotonEnergySpectrum1inPb.jpg | 800px]]

And, the results for this setup using 2 inches of lead between the detectors is as follows.

[[File:NeutronEnergySpectrum2Pb.jpg | 800px]]

[[File:PhotonEnergySpectrum2Pb.jpg | 800px]]

=Neutron Detector TDC Spectra Thick Uranium Target=

==8/17==
[[File:TDC8_17.png | 800 px]]

[[File:phi8_17.png | 800 px]]

[[File:theta8_17.png | 800 px]]

==8/20==
[[File:TDC8_20.png | 800 px]]

[[File:phi8_20.png | 800 px]]

[[File:theta8_20.png | 800 px]]

==8/21==
[[File:TDC8_21.png | 800 px]]

===4143===
[[File:TDC8_21_4143.png | 800 px]]

===4144===
[[File:TDC8_21_4144.png | 800 px]]

===4145===
[[File:TDC8_21_4145.png | 800 px]]

===4146===
[[File:TDC8_21_4146.png | 800 px]]

==8/22==
[[File:TDC8_22.png | 800 px]]

[[File:phi8_22.png | 800 px]]

[[File:theta8_22.png | 800 px]]

==8/23==
[[File:TDC8_23.png | 800 px]]

[[File:phi8_23.png | 800 px]]

[[File:theta8_23.png | 800 px]]

==8/24==
[[File:TDC8_24.png | 800 px]]

[[File:phi8_24.png | 800 px]]

[[File:theta8_24.png | 800 px]]

==8/17 - 8/20==
[[File:TDC8_17_20.png | 800 px]]

==8/17 - 8/21==
[[File:TDC8_17_21.png | 800 px]]

==8/17 - 8/22==
[[File:TDC8_17_22.png | 800 px]]

[https://wiki.iac.isu.edu/index.php/User:Jasenswanson Go Back]

File:Theta8 17.png

2012-10-02T16:56:16Z

Swanjase:

File:Phi8 17.png

2012-10-02T16:55:53Z

Swanjase:

2-Neutron Correlation

2012-10-02T16:55:19Z

Swanjase: /* 8/17 */

== Big Detector Solid Angle Calculations ==
[https://wiki.iac.isu.edu/index.php/Neutron_Corr Neutron Corr Home Page]
; MCNPX Simulation 
* 14 MeV neutron source, emitted isotropically (<math>4\pi</math>) 
* Detector placed 1m away from source 
[[File:mcnpxsetup.png | 500px]]

* face of the detector is 15.24cm x 76.2cm, and 3.6cm deep 
[[File:DetectorDimensions.png | 500px]]

The solid angle can be found from the number of particles hitting the detector as: 
<math>\Delta \Omega = 4\pi*\frac{hits}{hits + misses}</math>

; Results
* Out of 1E9 neutrons generated, 8618287 neutrons hit the detector
** <math>\Delta \Omega = 0.108 Sr</math>
*** if the detector is placed 70cm away from the source, <math>\Delta \Omega = 0.207 Sr</math>
*** if the detector is placed 65cm away from the source, <math>\Delta \Omega = 0.236 Sr</math>

* As a test to verify our results
** We change the detector size to 2cm by 2cm and used 1E9 neutrons again
** 32061 neutrons struck the detector
** <math>\Delta \Omega = 0.0004 Sr</math>

* And, as a second test to verify our results
** We change the detector size to 1cm by 1cm and used 1E9 neutrons again
** 7965 neutrons struck the detector
** <math>\Delta \Omega = 0.0001 Sr</math>

; Now, what neutron singles rate into the detector should correspond to 1 fission per pulse?
* If we have 1 fission per pulse and each fission emits on average 2.3 neutrons, we should expect 2.3 neutrons/pulse
* The number of neutrons hitting the detector per pulse is found as <math>2.3*\frac{\Delta \Omega}{4\pi}</math>
** @ 1 meter => 0.0198 neutrons hitting the detector per pulse
** @ 70 cm => 0.0379 neutrons hitting the detector per pulse
* Taking into account the efficiency of the detector <math>\epsilon_0</math>, the number detected per pulse can be found as <math>2.3*\frac{\Delta \Omega}{4\pi}*\epsilon_0</math>
** @ 1 meter from source => (<math>0.0198*\epsilon_0=0.0198*0.17=0.003</math>) neutrons detected per pulse
** @ 70 cm from source => (<math>0.0379*\epsilon_0=0.0379*0.17=0.006</math>) neutrons detected per pulse

==Neutron and Photon Flux Through Lead==

Using MCNPX, a simulation was done to determine how much of the neutrons and photons from the target will be blocked by various thickness of lead. With a monochromatic pencil beam of incident particles, the following results illustrate how much of the initial beam actually made it through the lead.

[[File:1MeV_Lead.jpg | 600px]]

[[File:5MeV_Lead.jpg | 600px]]

==Neutron and Photon Flux Through Concrete==

[[File:1MeV_Concrete.jpg | 600px]]

== Detector Cross-Talk ==

Using MCNPX, I am trying to simulated the cross-talk we could expect between the big detectors. I used a fission neutron energy spectrum given in MCNPX, shown below.

[[File:FissionNeutronEnergySpectrum.jpg | 800px]]

These neutrons are incident upon a plastic scintillator and I will look at the neutrons and photons coming out of the scintillator's sides perpendicular to the incident beam. The first case I will look at is where the detectors are placed with only polyethylene between them, as illustrated below.

[[File:OLead.png | 400px]]

This results in a neutron and photon energy spectrum as follows.

[[File:NeutronEnergySpectrum.jpg | 800px]]

[[File:PhotonEnergySpectrum.jpg | 800px]]

The next case I will look at is where we put a layer of lead between the polyethylene between the detectors, as shown in the schematic below.

[[File:DetectorSetupwLead.png | 400px]]

The results for this setup using 1 inch of lead between the detectors is as follows.

[[File:NeutronEnergySpectrumPb.jpg | 800px]]

[[File:PhotonEnergySpectrum1inPb.jpg | 800px]]

And, the results for this setup using 2 inches of lead between the detectors is as follows.

[[File:NeutronEnergySpectrum2Pb.jpg | 800px]]

[[File:PhotonEnergySpectrum2Pb.jpg | 800px]]

=Neutron Detector TDC Spectra Thich Uranium Target=

==8/17==
[[File:TDC8_17.png | 800 px]]

[[File:phi8_17.png | 800 px]]

[[File:theta8_17.png | 800 px]]

==8/20==
[[File:TDC8_20.png | 1400 px]]

==8/21==
[[File:TDC8_21.png | 1400 px]]

===4143===
[[File:TDC8_21_4143.png | 1400 px]]

===4144===
[[File:TDC8_21_4144.png | 1400 px]]

===4145===
[[File:TDC8_21_4145.png | 1400 px]]

===4146===
[[File:TDC8_21_4146.png | 1400 px]]

==8/22==
[[File:TDC8_22.png | 1400 px]]

==8/17 - 8/20==
[[File:TDC8_17_20.png | 1400 px]]

==8/17 - 8/21==
[[File:TDC8_17_21.png | 1400 px]]

==8/17 - 8/22==
[[File:TDC8_17_22.png | 1400 px]]

[https://wiki.iac.isu.edu/index.php/User:Jasenswanson Go Back]

2-Neutron Correlation

2012-10-02T16:54:59Z

File:TDC8 22.png

2012-08-23T20:37:52Z

Swanjase:

File:TDC8 21.png

2012-08-23T20:33:46Z

Swanjase:

File:TDC8 20.png

2012-08-23T20:33:08Z

Swanjase: