B (p,n) C - Revision history

RichardLefferts: parallel other reaction

2010-09-06T14:47:37Z

parallel other reaction

RichardLefferts: parallel to Al(p,n)Si page

2010-09-06T14:25:56Z

parallel to Al(p,n)Si page

RichardLefferts: New page: === 11C Identification and Measurement === Use 2 2" Sodium Iodide detectors. Manuafacturer is Bicron, now part of [http://www.detectors.saint-gobain.com/ Saint-Gobain] These detectors hav...

2010-08-27T09:21:37Z

New page: === 11C Identification and Measurement === Use 2 2" Sodium Iodide detectors. Manuafacturer is Bicron, now part of [http://www.detectors.saint-gobain.com/ Saint-Gobain] These detectors hav...

New page

=== 11C Identification and Measurement ===

Use 2 2" Sodium Iodide detectors. Manuafacturer is Bicron, now part of [http://www.detectors.saint-gobain.com/ Saint-Gobain]
These detectors have thin, havar windows because they were originally intended to measure light charged particles (proton, deuteron, triton, alpha) in light fusion reactions [http://prc.aps.org/abstract/PRC/v39/i1/p128_1 Paper from 1986]

NaI was one of the first inorganic scintillators discovered (reference) and is still widely used for x-ray and gamma ray detection. It has good "stopping power" or long "radiation length", ie, good ability to stop photons. The energy resolution is poor compared to CsI or BaF2 and is not even in the same league as HPGe. However, it is better than most organic scintillators.

The NaI scintillates in the (blue/uv/don't remember) and so is coupled to a photomultiplier with a (don't know) window. The PMT acts to increase convert the scintillation light into electrons then multiply the electron current until it is large enough for us to amplify or observe.

PMT

Tube BAse, Anode, dynode outs (these also have connections for Peltier Coolers [http://en.wikipedia.org/wiki/Thermoelectric_cooling Do NOt follow this link!!!]

NIM Bin

HV Power supply for Tube Base

Spectroscopy Amplifier, Unipolar + Bipolar outs, concept of GAin

Discriminator, CFD

Coincidence, Counter Timer

@@ Line 1: / Line 1: @@
 ==Background==
-The shorthand for this experiment indicates the basics of the process that will take place:
+In this experiment a proton fuses with <sup>11</sup>B nucleus then boils out a neutron to form the short lived isotope <sup>11</sup>C. We seek to identify <sup>11</sup>C by its half-life and to investigate the angular correlation of gamma-rays which we detect as a result of its decay.
-−
-<center><sup>27</sup>Al (p,n) <sup>27</sup>Si</center>
-−
-In other words, protons(p) of sufficient energy incident on an <sup>27</sup>Al target will fuse with the the nucleus and then emit a neutron(n), leaving <sup>27</sup>Si, where in both cases 27 indicates the atomic mass. This will only happen if the protons have sufficient kinetic energy to supply the difference in binding energy between <sup>27</sup>Al and <sup>27</sup>Si plus the difference between p and n masses.  At the <i>neutron threshold</i> energy the neutrons leave with no kinetic energy so a detailed energy balance can be done to measure the difference in binding n or p to a <sup>26</sup>Si core.
 ==Goals==
@@ Line 17: / Line 13: @@
 * Describe the ion optics principles and devices used in a low-energy heavy ion accelerator;
 * Develop and tune an ion beam to target using the accelerator facility;
-* Describe the principles behind neutron detection;
+* Describe the principles behind gamma ray detection;
-* Use a neutron detector (at present BF3), signal processing electronics (NIM based)and DAQ (at present a PCI MCA card and software) to collect data;
+* Use a gamma detector (NaI) and  signal processing electronics (NIM based)to collect count rates of correlated photons;
-* Analyze count rate versus beam energy data to extract the neutron threshold energy;
+* Analyze count rate versus angle to characterize the decay mode of <sup>11</sup>C;
 * Describe the nuclear physics meaning of their results.
@@ Line 39: / Line 36: @@
 ===Technique===
-To find the neutron threshold, we measure the neutron yield as a function of proton energy. Ideally, one would observe a small but gradually (linearly?) increasing background until one reached the threshold for fusion of the proton followed by evaporation of the neutron.  This yield will then increase (linearly) with beam energy. One can fit the data to two lines and extract their intercept.
+To create <sup>11</sup>C, we will conduct a fusion evaporation reaction with a proton beam and <sup>11</sup>B target.
-The literature guides us to want to scan the range of 5-7 MeV of proton energy. Step size should be chosen with regard to desired precision, target thickness and, of course, time constraints. When choosing how to scan over the energy range, one should consider beam activation of apertures in the beampipe and other sources of background neutrons.  Placing the detector at 0<sup>o</sup> in the lab frame is best because the low energy neutrons emitted just at threshold are very forward focussed.
+To run the experiment, we expose the <sup>11</sup>B target to the <sup>1</sup>H beam for approximately 2 half-lives of <sup>11</sup>C. We then remove the4 target to a beam-free room and use 2 sodium iodide detectors and associated electronics (NIM) to identify coincident events.
 ==Data Collection==
-As of September 2010, we will collect data for this experiment by taking timed energy spectra of the output of a [[Detectors | Boron Trifluoride] detector using an Ortec PCI Multichannel Analyzer (MCA) card and the Ortec software package Maestro.  One can use Maestro to implement cuts, background subtraction and integration of the spectra or export the data as comma-separated value (CSV) files for use in other software.
+As of September 2010, we will collect data for this experiment manually! The data are simply a table of counts per unit time versus time.
 ==Analysis==
-Ideally, one would observe a small but gradually (linearly?) increasing background of neutron yield until one reaches the threshold for fusion of the proton followed by evaporation of the neutron.  This yield will then increase (linearly) with beam energy. One can fit the data to two lines and extract their intercept.
+Ideally, one will see a simple exponential decay. The presence of contaminants has the potential to introduce other exponentials and complicate the fit.
 Return to [[Lab Manuals]]

@@ Line 1: / Line 1: @@
-=== 11C Identification and Measurement ===
+==Background==
-Use 2 2" Sodium Iodide detectors. Manuafacturer is Bicron, now part of [http://www.detectors.saint-gobain.com/ Saint-Gobain]
+The shorthand for this experiment indicates the basics of the process that will take place:
-These detectors have thin, havar windows because they were originally intended to measure light charged particles (proton, deuteron, triton, alpha) in light fusion reactions [http://prc.aps.org/abstract/PRC/v39/i1/p128_1 Paper from 1986]
-NaI was one of the first inorganic scintillators discovered (reference) and is still widely used for x-ray and gamma ray detection. It has good "stopping power" or long "radiation length", ie, good ability to stop photons. The energy resolution is poor compared to CsI or BaF2 and is not even in the same league as HPGe. However, it is better than most organic scintillators.
+<center><sup>27</sup>Al (p,n) <sup>27</sup>Si</center>
-The NaI scintillates in the (blue/uv/don't remember) and so is coupled to a photomultiplier with a (don't know) window. The PMT acts to increase convert the scintillation light into electrons then multiply the electron current until it is large enough for us to amplify or observe.
+In other words, protons(p) of sufficient energy incident on an <sup>27</sup>Al target will fuse with the the nucleus and then emit a neutron(n), leaving <sup>27</sup>Si, where in both cases 27 indicates the atomic mass. This will only happen if the protons have sufficient kinetic energy to supply the difference in binding energy between <sup>27</sup>Al and <sup>27</sup>Si plus the difference between p and n masses.  At the <i>neutron threshold</i> energy the neutrons leave with no kinetic energy so a detailed energy balance can be done to measure the difference in binding n or p to a <sup>26</sup>Si core.
-PMT
+==Goals==
-Tube BAse, Anode, dynode outs (these also have connections for Peltier Coolers [http://en.wikipedia.org/wiki/Thermoelectric_cooling  Do NOt follow this link!!!]
+At the completion of this experiment students will be able to:
-NIM Bin
+* Describe the principles behind the production of a negative ion beam;
-HV Power supply for Tube Base
+==Accelerator Operation==
-Spectroscopy Amplifier, Unipolar  + Bipolar outs, concept of GAin
+In order to acquire sufficiently energetic protons for this experiment, you will have to learn to create and direct a proton ion beam in the tandem accelerator. There are a number of components to the accelerator, which you will need to know the function of and how they will affect the nature of the proton beam.
-Discriminator, CFD
+===Components===
-Coincidence, Counter Timer
+<ul>