Difference between revisions of "Counting individual photons"

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== Meeting Notes ==
 
== Meeting Notes ==
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* [[January 30, 2007]]
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* [[May 21, 2008]]
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* [[February 15, 2007]]
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* [[May 13, 2008]]
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* [[March 1, 2007]]
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* [[May 6, 2008]]
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* [[March 28, 2007]]
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* [[April 29, 2008]]
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* [[April 5, 2007]]
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* [[April 22, 2008]]
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* [[April 17, 2008]]
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* [[April 1, 2008]]
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* [[March 11, 2008]]
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* [[February 28, 2008]]
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* [[February 14, 2008]]
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* [[January 31, 2008]]
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* [[January 25, 2008]]
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* [[January 17, 2008]]
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* [[ASR Meeting Notes 2007|Meetings from 2007]]
  
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== Diagram ==
 
  
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[[Image:Diagram_Glue-X.JPG|thumb|150px|Diagram of GlueX experiment]]
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== Research Project Pages ==
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The figure at the right shows the layout of the GlueX experiment. On the left is the tagging spectrometer and on the right is the GlueX spectrometer. Electrons from the accelerator pass through a diamond crystal just before they enter the tagging spectrometer. Interactions of the high-energy electrons in the diamond produce polarized gamma rays (red rays) of various energies. Most of the gamma rays have very small energy, but every once in a while an electron will have a direct collision with the diamond atoms and produce a gamma ray that carries away a large fraction of the electron's energy, and leave it with a lot less energy than it had when it came out of the accelerator. The gamma rays, both the low-energy and the high-energy ones, travel parallel to the electron beam when they are created. Inside the tagging spectrometer, however, the electrons are bent away from the gamma rays and travel along a curved trajectory (down in the figure) whose curvature depends on their energy.  Most of the electrons bend along the gently curve orbit shown in the figure and travel on to the beam dump (white) where they are stopped. 
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* [[Overview of the GlueX experiment]]
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[[Image:Tagger-schematic.jpg|thumb|150px|Schematic views of the GlueX tagger]]
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* [[My research paper]]
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The ones  that gave up a significant part of their energy to a gamma ray in the diamond are bent in a tighter orbit in the spectrometer than the rest, and come out of the spectrometer at the location indicated by the tagging detector (dark ellipse). These electrons correspond one-to-one with high-energy gammas (also called high-energy photons) in the photon beam (red line). The photon beam is not deflected by the magnetic field of the spectrometer, so it travels straight out the side of the magnet and is directed downstream toward the GlueX spectrometer. By lining up events in the GlueX spectrometer in time with electrons in the tagging detector, it is possible to "tag" the energy of each energetic photon that produces a high-energy interaction in the experiment.  This technique of indirectly measuring the photon beam energy on a photon-by-photon basis by detecting the electron that created it is known as "photon tagging".
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* [[Poster from Westport Science Fair]]
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* [http://zeus.phys.uconn.edu/~jonesrt/students/jzhao/suitability-4-2-2007.ppt Presentation to ASR peers on April 2, 2007]
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* [http://zeus.phys.uconn.edu/~jonesrt/students/jzhao/jie-5-2007.ppt Presentation at Science Symposium April 23, 2007]
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* [[Media:TemponDark.ppt|ASR first semester project presentation, 2007/8]]
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* [[Method for determining how many photons are in a pulse]]
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* [[My List of Research Articles on Photon Detection|My list of research articles on photon detection]]
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* [http://zeus.phys.uconn.edu/halld/siliconPM/ Directory of Papers on Silicon Photomultipliers in High Energy Physics Experiments]
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* [[Advantages of the SiPM]]
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* [[SiPM Used]]
  
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== Drafting of Research Paper 10 - 2006 ==
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* [[Prediction]]
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* [http://zeus.phys.uconn.edu/wiki/images/Jzhao-10-2006.pdf Paper 10-2006 revision 1]
 
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* [http://zeus.phys.uconn.edu/wiki/images/Jzhao-10-2006_r2.pdf Paper 10-2006 revision 2]
 
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* [http://zeus.phys.uconn.edu/wiki/images/Jzhao-10-2006_r3.pdf Paper 10-2006 revision 3]
 
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== Poster from Westport Science Fair ==
 
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{|
 
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||[[Image:Poster_v1_(main).JPG|thumb|150px|main poster]] ||[[Image:Poster_v1_(center_top).JPG|thumb|150px|center top]] ||[[Image:Poster_v1_(center_bottom).JPG|thumb|150px|center_bottom]]
 
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|}
 
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== Measured pulse photon count ==
 
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[[Image:Pulses_Detected.JPG|thumb|150px|Data]] ||
 
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At the right is a snapshot of the pulses produced by a hybrid photodiode (HPD, blue trace) illuminated by a blue light-emitting diode (LED, yellow trace).  The average number of photons detected by the HPD per pulse is computed by taking the integral of the charge in a single pulse and dividing it by the average charge per photoelectron in the HPD.  The manufacturer (DEP, Netherlands) specifies that the HPD collects 2700 ''e''<sup>-</sup> of charge per photoelectron produced in the cathode.  The signal from the HPD was not amplified.  It was measured in Volts by the oscilloscope with a 50&Omega; terminating resistor.  The blue trace in the figure displays 20 mV per division, which becomes 0.40 mA / division after dividing by R=50&Omega;
 
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<math>\int\ {f(x)}\, dx \approx 1000\ photons</math>
 

Latest revision as of 18:57, 21 May 2008

Meeting Notes


Research Project Pages

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