Home » Posts tagged 'Electronvolt'

Tag Archives: Electronvolt

Doubt on Alpha Rays

Alpha rays are helium nuclei since they have two protons and no electrons. They are He 2+ ions. However we have learnt that helium has highest ionization energy  and an extremely large amount of energy is needed for it to form an ion. According to this, it is not possible for a dipositive cation of helium to exist, however it does . What could be the reason?



First of all Alpha particle is not a doubly ionized Helium Atom. It is emitted from the nucleus of a discintegrating atom.

The "curve of binding energy": A gra...


The energy required to peel off the two electrons is not too much as compared to the energy  involved in the alpha particle emission which is a nuclear reaction. Alpha particles are normally emitted as a part of radio active disintegrations, emitted by naturally unstable nuclei or artificially instabilized nuclei.


The ionization energy of helium is discussed in the purview  of the energy required to remove the electrons. Helium is having a stable duplet electronic configuration which makes it a stable atom. But the energy considerations in nuclear reactions are very much different and higher.


The first ionization energy of helium  is 2372.3 kJ/mol and the second ionization energy is 5250.5 kJ/mol


16 MeV = 16×1.6×10-13 J per nucleus 2.56 x 10-12 J per nucleus


which makes of the order of 1010 kJ per mol of Helium. This is evidently a huge amount compared to that of the ionization energy.


Basically there are a number of differences between chemical reactions and nuclear reactions.


1. In chemical reactions the electrons are taking part in reactions whereas in nuclear reactions the nucleons (protons and neutrons) are involved


2. In nuclear reactions the energy involved is very much large as compared to that in chemical reactions


3. The identity of the element dioes not change in chemical reactions whereas the identity is changed in most of the nuclear reactions.



Can the process of Pair Production be used as a source for energy generation in space?

Can the process of Pair Production

Creation of an electron and a positron by Pair...
Creation of an electron and a positron by Pair production. (Photo credit: Wikipedia)

be used as a source for energy generation in space?  Can Gamma Rays in space become the source for generating  energy using Pair Production process?  EM radiation >1.02 MeV enery, Pair Production is the dominant absorption process.

(Posted By Chintan Shah)

Have an answer? Post as comment now!

How do the protons fly almost at a speed of light in LHC at CERN?

How do the prortons fly almost at a speed of light in LHC at CERn.What gives them so much acceleration?please clarify…If i want to study Particle physics in future what qualifications I would need.I want to be a scientist at CERN?Please clarify.

Posted by Nabasindhu DAs

Response from AskPhysics Team

An example of simulated data modelled for the ...

Hi! First of all we would like to congratulate you on your wish and dream to join CERN.

The acceleration of protons are done by huge particle accelerators.

The Currently active machines are:
Two linear accelerators generate low energy particles. Linac2 accelerates protons to 50 MeV for injection into the Proton Synchrotron Booster (PSB), and Linac3 provides heavy ions at 4.2 MeV/u for injection into the Low Energy Ion Ring (LEIR).[16]
The Proton Synchrotron Booster increases the energy of particles generated by the proton linear accelerator before they are transferred to the other accelerators.
The Low Energy Ion Ring (LEIR) accelerates the ions from the ion linear accelerator, before transferring them to the Proton Synchrotron (PS). This accelerator was commissioned in 2005, after having been reconfigured from the previous Low Energy Antiproton Ring (LEAR).
The 28 GeV Proton Synchrotron (PS), built in 1959 and still operating as a feeder to the more powerful SPS.
The Super Proton Synchrotron (SPS), a circular accelerator with a diameter of 2 kilometres built in a tunnel, which started operation in 1976. It was designed to deliver an energy of 300 GeV and was gradually upgraded to 450 GeV. As well as having its own beamlines for fixed-target experiments (currently COMPASS and NA62), it has been operated as a proton–antiproton collider (the SppS collider), and for accelerating high energy electrons and positrons which were injected into the Large Electron–Positron Collider (LEP). Since 2008, it has been used to inject protons and heavy ions into the Large Hadron Collider (LHC).
The On-Line Isotope Mass Separator (ISOLDE), which is used to study unstable nuclei. The radioactive ions are produced by the impact of protons at an energy of 1.0–1.4 GeV from the Proton Synchrotron Booster. It was first commissioned in 1967 and was rebuilt with major upgrades in 1974 and 1992.
REX-ISOLDE increases the charge states of ions coming from the ISOLDE targets, and accelerates them to a maximum energy of 3 MeV/u.
The Antiproton Decelerator (AD), which reduces the velocity of antiprotons to about 10% of the speed of light for research into antimatter.
The Compact Linear Collider Test Facility, which studies feasibility issues for the future normal conducting linear collider project.

The LHC is the world’s largest and highest-energy particle accelerator

The collider is contained in a circular tunnel, with a circumference of 27 kilometres (17 mi), at a depth ranging from 50 to 175 metres (160 to 574 ft) underground.

Prior to being injected into the main accelerator, the particles are prepared by a series of systems that successively increase their energy. The first system is the linear particle accelerator LINAC 2 generating 50-MeV protons, which feeds the Proton Synchrotron Booster (PSB). There the protons are accelerated to 1.4 GeV and injected into the Proton Synchrotron (PS), where they are accelerated to 26 GeV. Finally the Super Proton Synchrotron (SPS) is used to further increase their energy to 450 GeV before they are at last injected (over a period of 20 minutes) into the main ring. Here the proton bunches are accumulated, accelerated (over a period of 20 minutes) to their peak 7-TeV energy, and finally circulated for 10 to 24 hours while collisions occur at the four intersection points.

More technical details can be had at the following links, including the ways to join CERN

Work done in accelerating a proton

The mass of a proton is 1840 times that of an electron. it is accelerated to a potential difference of 1kV. find the amount of work done in process. (Ujjwal Sharma asked)


The work done = the KE acquired = eV=1.6 x 10-19 x 1000 = 1.6 x 10-16 J

Visitors So Far @ AskPhysics

  • 2,045,383 hits

Subscribe to Blog via Email

Enter your email address to subscribe to this blog and receive notifications of new posts by email.

Join 4,000 other subscribers


%d bloggers like this: