Pair Definition and 400 Threads

Hello, I have a [probably silly] question regarding particle pair production in strong static fields. Take for instance the finite Coulomb field (of say an extended nucleus) and the Dirac equation. One can compute the bound states of such a system and see that at a certain value of Z the...

when a photon interacts with a nucleus, a positron and an electron are created, provided the photo has enough energy. But what is the probabilty of this occurring? If i fire 100 photons at a nucleus, how many electron-positron pairs will i create? Also, has anyone ever succeeded in...

Good afternoon! 1. The Setup One block of Mass M2 is resting on top of a frictionless surface. Another block, M1, is resting on top of the of the first block. There does exist a coefficient between these two blocks, μ. 2. What happens to the bottom block when a force less than μN is...

Greetings, I know that when encrypting something with the public key of a key pair, the encrypted data can only be decrypted with the private key of the pair. And it can not be decrypted with the public key that was just used. I do not understand how it is possible to perform a mathematical...

Hello, I'm reading something about adsorbate induced surface resistivity changes in thin metal films and there is often mentioning of electron-hole pair damping, as for example: "electron-hole pair damping of the parallel(to the surface of thin film) frustrated vibration of the...

Hi, i have a few questions about these two processes. Now, I am only 16 years old, in my last year of school, so I am not so familiar with physics, if you could put terms simple enough for an average 16 year old to understand, i'd much appreciate it :) my question is: If e‾ + e+ → γ + γ and γ →...

I've done 3 wilcoxon matched pair tests and was wondering if someone could give me some advise on the most logical / correct way to report the results. test 1: pre post 1.98 1.56 1.09 2.49 2.18 2.94 1.13 1.29 1.23 2.38 result: Z = -1.438, two tail p = 0.138 So I was...

Homework Statement A gamma-ray photon produces an electron-positron pair, each with a kinetic energy of 285 keV. What was the energy of the photon? Homework Equations E = mc2 hf = KEmax +W0 The Attempt at a Solution E = 2(9.11*10^-31 kg)(3.0*10^8 m/s)^2 = 1.64*10^-13 J = 1.02 MeV This...

I am trying to find out the density of electron positron pairs around a bare electron charge. In most texts, I saw that the treatment relates to the observed charge vs. the bare charge. I wanted to know if there is a formula that describes the density of electron positron pairs that surround...

Homework Statement Since no one wants to answer my heat conductor problem (*hint hint*), here's a more interesting one. If it is assumed that all (52 choose 5) poker hands are equally likely, what is the probability of being deal one pair? (This occurs when the cards have denominations a, a...

Homework Statement The question asks me to construct a pair of sequences {a_n} from n=1 to inf and {b_n} from n=1 to inf such that a_n and b_n are both greater than or equal to zero for all integers n, both sequences are decreasing, and both series of these sequences diverge, but also such...

Does anyone know if there is a non-Euclidean geometry(or something like that) where the circle becomes a line or a pair of parallel lines? ...or even where the circle becomes a set of parallel lines? ...i'm doing some work in Guitar Theory and this situation appears... Thanks The...

Hi All, I get that one object can't travel faster than light with respect to another object because of SR and length and time contraction. What I don't get is how this meshes up with expanding universe. If the space between 2 objects is expanding then wouldn't two objects be accelerating...

I think its true that you cannot use a bubble chamber to identify the pair production of a neutron-antineutron pair, but how (maybe if) is that studied? Is that reaction common in a proton collider?

Homework Statement How much energy is required to produce the electron-positron pair in the filed of nucleus (Z=20) if electron is captured to the ground 1s state of the system. The Attempt at a Solution I can calculate the energy of the captured electron from E = - εZ2/(2n2) where...

Homework Statement two photons collide head-on and create an electron and an anti electron. The energy of photon 1 is given, but not for photon 2. Find the velocity β of the systems rest frame (where the total momentum is zero.) Homework Equations β=v/c γ=1/√1-β^2) β=pc/E The...

Homework Statement There are two noninteracting, spinless, distinguishable particles an isotropic oscillator potential. One particle is in the state |1\rangle =\frac{1}{\sqrt{2}}(|1,1,-1\rangle + |1,1,0\rangle ) and the other is in the state |2\rangle = \frac{1}{\sqrt{2}}(|1,1,0\rangle -...

A positron and an electron are simultaneously fired from paralle particle accelerators a distance d apart, with equal velocity v. One calculation says that each one will, being a moving charged particle, induce a magnetic field B=\frac{\mu_0 q v}{4\pi d^2} and since the other is moving in...

If we assume that the Twin Prime Conjecture is true (and thus there are infinite number of primes that are 2 apart), how reasonable is it to assume that there will be an infinite number of Twin Primes that are preceded by a prime that is at least 10 lower than the first of the Twin Primes? (I...

Hi, I was reading some novice stuff about quantum entanglement and I was wondering if entanglement occurs in either of these two scenarios: 1. electron and positron entangled as a result of being created by a photon passing over a heavy nucleus 2. two free electrons entangled with...

I'm reading about ion chromatography at the moment and read that one method is to use an ion-pair reagent which pairs with the ionic analyte, forming a neutral compound which can then partition into the non polar stationary phase. If an anionic analyte pairs with a cationic ion-pair reagent to...

I am learing the particle physics bit of my physics course and don't understand how momentum is conserved when a photon produces an electron/positron pair. In the bubble chamber chamber picture here...

My friend said that two horses pull the Magdeburg hemispheres with same force is as same as a horse pulls the Magdeburg hemispheres which is tell on a tree(I may forget the details about the assumption) Why? Another Q. about action and reaction i don't know why the reading isn't 2Mg,but is...

Can anyone help me, I am some what unclear on the reason why "conventional" superconductors have cooper pairs only in the singlet state. Is it something to do with the expectation values given for the separate states calculated from their spatial and spin wave functions? For example does the...

Homework Statement See first figure attached for problem statement. Homework Equations The Attempt at a Solution I've solved everything in this circuit, I just have some confusion about solving V_{CMmin} when I have a current mirror acting as my current source connected to the...

Homework Statement See first figure attached. Homework Equations The Attempt at a Solution See 2nd figure attached for my work so far at attempting the design. The last figure is what my textbook gives as the small signal analysis of a BJT differential amplifier with emitter...

My understanding is that when a particle-antiparticle pair is created, they will have opposite spins and momenta. So the net momentum will be zero. But doesn't the momentum depend on the frame of reference? Say the particles both have mass m and velocities +v and -v. Then the net momentum is...

Hello, This may sound silly, don't be afraid to let me know just how silly though! I've read that predictions are made using the standard model. I do not know the details of this process. I understand pair production occurs randomly in a vacuum, but I wondered if there was an underlying...

Why is that in twisted pair cable, the tighter the twisting, the higher the supported transmission rate? Thankyou

I've gotten interested in this pair production stuff, and I'm wondering: Why is it that some nuclei can absorb more energy than the energy needed for pair production, while other nuclei result with the incoming energy creating pair production? Is it because heavier nuclei can distribute the...

During electron-positron pair production, does electron capture always happen? Gracias

Hi, Someone told me that a potential of 10^6 volts is not stable because it would cause spontaneous electron-positron creation from the vacuum. Is this true? I thought one could reach higher potentials than 1000000 volts.

Hello, In a previous discussion of Pair production I was shocked by what I heard and I have some questions from the general explanation of the subject. So you can make fermions out of bosons? You can make rest mass out of energy? Does this mean that not just relativistic mass, but...

I was reading about electron-positron annihilation and I got to the part where it says that this is a reversible process, meaning that an electron and a positron could be created from photons. About this reverse process the article says "In nuclear physics, this occurs when a high-energy photon...

My grasp of physics is limited, however, I am an engineer, thus I am asking for other's assistance in understanding how to delay the annihilation of a virtual particle pair. Most literature I've read, indicates a virtual particle pair is "real" if only briefly. QUESTION: How long is...

I have been trying to solve the inverse Fourier transform: \int_{-\infty}^{\infty}\left[e^{-j2\pi ft_0}e^{j\theta}\right]e^{j2\pi ft}df I know that the Fourier transform pair says e^{-j2\pi ft_0}e^{j\theta} \leftrightarrow \delta(t-t_0) but the extra phase term e^{j\theta} makes...

The ordered pair <-3,2> represents vector XY. Give possible coordinates for X and Y? Homework Equations The Attempt at a Solution I really have no clue how to even attempt this problem since I haven't ever been given such a problem. Could I get any help please?

Hey guys, I just found out about these darlington transistors, and I read that the purpose of these transistors are to "amplify WEAK signals". After taking a look at the circuit diagram for the darlington pairs, it seems to me that it is just 2 npn bjts with one of the bjt's emitter...

Although there is no experimental evidence or QG theory, it is not unreasonable that very strong gravitational fields or very high energy gravitons would cause pair production of real particles. In view of the spin-2 nature of gravity, what might these pairs be? One electron, one positron and...

Homework Statement I'm given this interaction Lagrangian: L_I (x) = -g \overline{\psi}(x) \psi (x) \phi (x) where g is the coupling constant, \psi is an electron and \phi is a neutral scalar field. I have to calculate the amplitude for process \psi + \psi \rightarrow e^- + e^+ that...

If in a given DNA molecule a C-G base pair is changed to a U-G base pair the following mutational change in the DNA will result a. C-G to G-C b. C-G to T-A c. C-G to A-T d. C-G to A-U Can someone elaborate on this for me?

Homework Statement This is a special relativity question: Two gamma rays of identical energies E collide with an angle \theta between their velocities. Show that positron-electron pair creation is impossible in the limiting case \theta=0. Find the minimum \theta value for p-e creation to...

Hello. I have understood the Kuratowski definition of the ordered pair and appreciate it's usefulness but have a nagging difficulty about it. Consider an ordered pair which is (a,a). according to Kuratowski definition it is defined as {{a},{a,a}} . Now consider an ordered triplet (a,a,a) it...

Hi, I'm building a pair of helmholtz coils to do a variety of magnetism-related experiments. I've borrowed an old Avo Douglas coil winder and plan to do a couple of thousand turns on two sections of 50mm or 60mm diameter pipe. Some nylon threaded rod will pass through the middle of each coil...

Consider a proton and antiproton collision. The goal is to produce a top quark and anti-top quark pair. If a top quark has a mass of 174 GeV/c2, how much energy is required in the center of mass frame to produce the combination? I'm somewhat utterly stumped. Obviously, the problem deals with...

Hello, Would it be possible for an electron and positron to form a cooper pair if an electron is brought into the neighborhood of the positron who is anchored in a penning trap (or in some other fashion)? If normal cooper pairs form by using the the attractive force of the lattice...

I was looking at a picture (attachment) in a physics website and the following doubt arose: I previously thought that the weight of the block (gravitational pull of the Earth on the block) caused a reaction force of the table, but now, from what I understand and, please correct me if I am...

Homework Statement http://nplq1.phyast.pitt.edu/res/csm/csmphyslib/type66_inductance/PairOfCoils.jpg Coil A is a large 400 turn circular coil of radius 91.0 cm. Circular coil B has 160 turns, a radius of 2.0 cm and is located L = 92.0 cm from coil A along the same axis. The planes of the two...

Homework Statement what is the minimal wavelength of electromagnetic radiation to pair-produce an electron-positron pair? Homework Equations ~ = wavelength hc/~ = 2MeC^2 + K The Attempt at a Solution hc/~ = 2MeC^2 = 2(9.11x10^-31)(3x10^8)^2 ~ = 8.24x10^-11m is tis correct?

I never understood this how do 2 like charges stay together, the electro is it like eddy currents or something