Mass stopping power

The mass stopping power, /p, is commonly expressed in units of MeV/g cm. ... 

Mass energy absorption coefficient Mass stopping power... 

Bethe theory for heavy charged particles In 1932 Bethe [27-29] developed a new collision stopping power theory to take into consideration both quantum mechanical and relativistic effects. For heavy charged particles, Bethe found the non-relativistic expression for the mass stopping power to be [25]... 

The spin-exchange contribution to the overall mass stopping power becomes important for energies below 25 eV. 

Stopping Power—The average rate of energy loss of a charged particle per unit thickness of a material or per unit mass of material traversed. 

Straggling thus limits the depth and mass resolution for features buried within the target material. The depth resolution, Az depends on the stopping power, dE/dz, the detector resolution, AEdet and the beam energy spread, AEbeam of the incident particles ... 

Thus, the average stopping power is proportional to the initial energy except for corrections due to atomic collisions (electronic excitation) near 108 eV. For a medium of nuclear charge Ze and mass number A, the radiation length is given by (Bethe and Ashkin, 1953)... 

The depth-profile of photon absorption is analogous to that for UV-visible light, i.e. I = Io exp(-Ad), where the mass energy absorption coefficient, u/g is used instead of the extinction coefficient. Particulate energy absorption can be described by relative stopping powers. 

The dotted lines in Fig. 1 show the stopping powers for the different ions at a constant velocity in units of MeV/amu. This unit of energy is very often used in heavy ion radiolysis and it is based on the classical formula for kinetic energy, E = V2 MV, where M is the heavy ion mass. As seen in Eq. (1), the ion velocity is a dominant parameter in energy loss processes and the MeV/amu energy unit is more convenient to use than converting to absolute velocity units. Remember that MeV/amu is actually proportional to the square of the velocity. 

The electronic stopping power involves a collision between the heavy ion nucleus and an electron of the medium. The reduced mass of the encounter can always be assumed to... 

In radiation studies it is conventional to relate the magnitude of the effect to the energy absorbed by unit mass.331 Usually one takes the stopping power Sem = dE/p dx. Introducing the mass emissive power with... 

The efficiency of the detection system is based on both detector and sample parameters. Detector parameters include the intrinsic detector efficiency, the geometric relation of detector to sample, scattering by the sample support and nearby material, and attenuation between the sample and the detector. Sample parameters include material stopping power based on composition, mass, diameter and thickness type and amount of sample cover and backing and radiation type, energy, decay fraction, and decay rate. 

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