Presentation Tzu-Cheng, Chuang ( 莊子承 ) Exchange understudy from National Tsing-Hua University (Taiwan) ( 國立清華大學 , 台灣 )Slide 2
Where? Russia China Japan TaiwanSlide 3
Zoom in China Taiwan Hong Kong MacauSlide 4
Who is from Taiwan? Manure Hai, Lee ( 李東海 ) Theoretical consolidated matter Physicist Yuen-Ron, Shen ( 沈元壤 ) Professor Emeritus Condensed Matter Physics And Materials ScienceSlide 5
And… Frank Hsia-San Shu ( 徐遐生 ) Astrophysicist Department of Astronomy Department seat from 1984-88 The previous president of National Tsing-Hua Univ. from 2002 ~ 2006 He was regarded as the beneficiary of a year ago\'s (2008) Harvard Centennial Medal The Harvard Centennial Medal, front and back (Source: Harvard University site)Slide 6
Positronium (Ps) TOPIC:Slide 7
Outline Introductions Who anticipated and who found positronium States Energy Levels ApplicationsSlide 8
Introduction First What is the Positronium? Is it identified with Positron & Electron?Slide 9
Positronium(Ps) Metastable bound condition of e + and e - An Exotic molecule Energy level : like the hydrogen iota (why?) Exactly same as hydrogen? (lessen mass) Positronium HydrogenSlide 10
Introductions Who anticipated and who found positronium States Energy Levels ApplicationsSlide 11
Who anticipated positron? Who found positronium? Second Is it essential? Two people won the Nobel Prize on account of this!Slide 12
Who anticipated? Carl Anderson anticipated "positron" presence in (1905-1991) 1932 while at Caltech March 15, 1933, PRL, V. 43, The Positive Electron, Carl D. Anderson Nobel Prize in Physics in 1936 for PositronSlide 13
Who found? Martin Deutsch the physicist who first ( 1917 – 2002) identified positronium in Gas He took a shot at the Manhattan Project and educated at MIT Nobel Prize in 1956 for finding PsSlide 14
Introductions Who anticipated and who found positronium States Energy Levels ApplicationsSlide 15
States Third Ground state? energized states?… or United States?Slide 16
What we know Electron – turn : ½ Positron – turn : ½ Ground state : like hydrogen It\'s the same as HYDROGEN ! Why? Expansion of Angular Momentum: S = 0 v 1, m = - 1, 0, 1 So what would we be able to anticipate? Singlet Triplet stateSlide 17
Singlet State Singlet state : against parallel twists (S=0, ) It is called para-positronium (Abbr. p-Ps ) 1. Mean lifetime : 125 picoseconds 2. Rots specially into two gamma quanta , which transmitted from Ps destruction , with vitality of 511 keV every Selection administer Mean lifetime ( ) λ is a positive number called the rot steady. Rot work http://www.blacklightpower.com/FLASH/Positronium.swfSlide 18
Singlet (cont.) Doppler Broadening to gauge the vitality of the gamma beams utilizing a high-immaculateness Germanium indicator For stationary Ps, we would anticipate that the vitality range will comprise of a thin top at 511 keV the vitality anticipated by Einstein\'s E=mc 2Slide 19
Singlet (cont.) p-Ps 1. rot into any considerably number of photons 2. the likelihood rapidly diminishes as the number expands Ex: The spreading proportion for rot into 4 photons is 1.439×10 - 6 Negligible! p-Ps lifetime (S = 0): * S. G. Karshenboim, Precision Study of Positronium: Testing Bound State QED TheorySlide 20
Triplet State Triplet state : parallel twists ( ) It is called ortho-positronium ( o-Ps ) * 1. In vacuum has a mean lifetime of 142.05±0.02 nanoseconds 2. The main method of rot is three gamma quanta . Odd number of photon How is alternate methods of rot? Insignificant! Ex: Five photons mode\'s spreading proportion is 1.0* 10 - 6 A. Badertscher et al. (2007). "An Improved Limit on Invisible Decays of Positronium". Phys Rev D 75Slide 21
Triplet State Cont. Ortho-positronium lifetime (S = 1): * How about the other state? In the 2S state is metastable having a lifetime of 1.1 μs against demolition. In such an energized state then it will rapidly course down to the ground state where destruction will happen all the more rapidly S. G. Karshenboim, Precision Study of Positronium: Testing Bound State QED TheorySlide 23
Introductions Who anticipated and who found positronium States Energy Levels ApplicationsSlide 24
Energy levels ForthSlide 25
Energy Levels Using Bethe-Salpeter condition the closeness amongst positronium and hydrogen considers a harsh gauge The vitality levels are distinctive between this two on account of an alternate esteem for the mass , m* , utilized as a part of the vitality condition So how to figure it?Slide 26
Energy Level (Cont.) Electron vitality levels in Hydrogen: But now we change the mass, m, to diminished mass , μ Where are the mass of electron and positron which are the sameSlide 27
Energy Level (Cont.) So now we change the condition to The vitality is the half of the hydrogen level The most reduced vitality level of positronium (n = 1) is −6.8 electron volts (eV). The following most noteworthy vitality level (n = 2) is −1.7 eV, the negative sign infers a bound stateSlide 28
Conclusion Ps is a bound state between a positron and an electron Can be dealt with formally as a hydrogen particle The Schrödinger condition for positronium is indistinguishable to that for hydrogen Positronium is essentially shaped in two states, ortho-positronium with parallel twists (triplet state) para-positronium with against parallel twists (singlet express) The vitality contrast between these turn states (hyperfine split-ting) is just 8.4x10 - 4 eVSlide 29
Experiment Sample: NO (nitric oxide) In a gas containing atoms with an odd number of electrons, the triplet state would be changed over quickly to the singlet A little admixture of NO �� fast obliteration of those positron which would have rotted by three-quantum destruction with time of 10 - 7 * A. Metal, Yearbook 1949 (University of Bergen). No, 12.Slide 30
Experiment (cont.)Slide 31
Before another point Physics can be valuable in our lifeSlide 32
Introductions Who anticipated and who found positronium States Energy Levels ApplicationsSlide 33
Application FifthSlide 34
Application What machine utilizes this idea? Section 2 Nuclear Cardiology: Technical Applications By Gary V Heller, April Mann, Robert C. Hendel Edition: delineated Published by McGraw Hill Professional, 2008 ISBN 0071464751, 9780071464758 352 pagesSlide 35
Positron outflow tomography (PET) 1. An atomic pharmaceutical imaging procedure which delivers a three-dimensional picture of utilitarian procedures in the body 2. The framework recognizes sets of gamma beams transmitted in a roundabout way by a positron-emanating radionuclide (tracer) Image of an average positron outflow tomography (PET) officeSlide 36
PET (cont.) How can it work? A brief radioactive tracer isotope is infused into the living subject Waiting for some time until the dynamic atom gets to be distinctly gathered in tissues of intrigue The protest is put in the imaging scanner During the output a record of tissue focus is made as the tracer rotsSlide 37
PET (cont.) As the radioisotope experiences positron discharge rot , it radiates a positron After flying out up to a couple of millimeters the positron experiences an electron, delivering a couple of demolition (gamma) photons moving in inverse bearings These are identified when they come to a scintillator in the examining gadget, making a burst of light which is recognized by photomultiplier tubes The strategy relies on upon concurrent or incidental discovery of the match of photons; photons which don\'t land in sets (i.e. inside a planning window of couple of nanoseconds) are overlookedSlide 38
PET (cont.) Detect the light, then procedures the information Creating a burst of light The gadget recognizes the positronSlide 39
PET Cont. Restriction of the positron destruction occasion The most huge part of electron-positron rots result in two 511 keV gamma photons being discharged at right around 180 degrees to each other; thus it is conceivable to limit their source along a straight line of occurrence (additionally called formally the line of reaction or LOR )Slide 40
PET (cont.)Slide 41
PET (cont.) Image reproduction utilizing incident insights Using measurements gathered from a huge number of happenstance occasions A guide of radioactivities as a component of area for bundles or bits of tissue, might be built and plotted The subsequent guide demonstrates the tissues in which the sub-atomic test has turned out to be thought, and can be deciphered by an atomic prescription doctor or radiologist with regards to the patient\'s conclusion and treatment arrangeSlide 42
PET (cont.)Slide 43
PET (cont.) Only the match of photons would be recorded! Positron transmitsSlide 44
Before we end this presentationSlide 45
What teacher said the AMO Nobel Prize Winner, Prof. Carl Wieman, this "smooth" approach DOES NOT REALY WORKSlide 46
Reference Y. Nagashima , et al., Thermalization of free positronium iotas by crashes with silica-powder grains, aerogel grains, and gas atoms. Phys. Rev. A 52, 258 (1995). J. E. Blackwood, et al., Positronium scrambling by He. Phys. Rev. A 60, 4454 (1999). J. E. Blackwood, et al., Positronium disseminating by Ne, Ar , Kr and Xe in the solidified target estimation. J. Phys. B 35, 2661 (2002). K. F. Trot, et al., Positronium destruction in low-temperature uncommon gasses. I. He. Phys. Rev. A 12, 375 (1978). G. Peach, Positron Spectroscopy of Solids, altered by A. Dupasquier and A.P. Plants, Jr. (IOP, Amsterdam, 1995), p. 401, refered to by G. Laricchia . M. Skalsey , et al., Doppler-expanding estimations of set
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