Related Experiment Video
Updated: Jul 26, 2026
14:11
Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis
Published on: March 29, 2016
Measurement of structure-dependent K+ --> &mgr;(+)nu(&mgr;)gamma decay
Physical Review Letters
|September 8, 2000
Summary
Researchers measured a structure-dependent component in the rare Kaon (K+) decay into a muon (μ+) and neutrino (νμ) with a photon (γ). This study provides crucial data on fundamental particle interactions and the Standard Model.
Area of Science:
- Particle Physics
- High Energy Physics
- Kaon Decays
Background:
- Kaon decays offer insights into the Standard Model of particle physics.
- Understanding rare decays like K+ → μ+νμγ is crucial for testing theoretical predictions.
Purpose of the Study:
- To report the first measurement of the structure-dependent component in the K+ → μ+νμγ decay.
- To determine the absolute value of the sum of vector and axial-vector form factors, |F(V)+F(A)|.
- To calculate the branching ratio for this specific decay mode.
Main Methods:
- Analysis of the K+ → μ+νμγ decay in a specific kinematic region.
- Selection criteria based on muon kinetic energy (>137 MeV) and photon energy (>90 MeV).
- Extraction of form factor values and branching ratio from experimental data.
Main Results:
- The absolute value of the sum of vector and axial-vector form factors was determined to be |F(V)+F(A)| = 0.165 ± 0.007 ± 0.011.
- The branching ratio for the structure-dependent positive component was found to be B(SD+) = (1.33 ± 0.12 ± 0.18) × 10^-5.
- A 90% confidence level limit was set for the difference between vector and axial-vector form factors: -0.04 < F(V)-F(A) < 0.24.
Conclusions:
- This study presents the first measurement of a structure-dependent component in K+ → μ+νμγ decay.
- The results provide valuable experimental data for refining theoretical models of weak interactions.
- The findings contribute to a more precise understanding of fundamental particle physics parameters.
Related Concept Videos
03:18Radioactivity and Nuclear Equations
Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for hydrogen, neutrons. The number of protons in the nucleus is called the atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same element.
A nuclide of an element has a specific number of protons and...
A nuclide of an element has a specific number of protons and...
03:23Types of Radioactivity
The most common types of radioactivity are α decay, β decay, γ decay, neutron emission, and electron capture.
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay:
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
02:13Nuclear Binding Energy
The difference between the calculated and experimentally measured masses is known as the mass defect of the atom. In the case of helium-4, the mass defect indicates a “loss” in mass of 4.0331 amu – 4.0026 amu = 0.0305 amu. The loss in mass accompanying the formation of an atom from protons, neutrons, and electrons is due to the conversion of that mass into energy that is evolved as the atom forms. The nuclear binding energy is the energy produced when the atoms’ nucleons are bound together;...
02:59Biological Effects of Radiation
All radioactive nuclides emit high-energy particles or electromagnetic waves. When this radiation encounters living cells, it can cause heating, break chemical bonds, or ionize molecules. The most serious biological damage results when these radioactive emissions fragment or ionize molecules. For example, α and β particles emitted from nuclear decay reactions possess much higher energies than ordinary chemical bond energies. When these particles strike and penetrate matter, they produce ions...
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.