INAA
Definition
Instrumental Neutron Activation Analysis. The whole sample is irradiated, cooled, and counted directly. No wet chemistry. Non-destructive.
- Full name
- Instrumental Neutron Activation Analysis
- Sample prep
- No wet chemistry required
- Sample impact
- Non-destructive
- Process
- Irradiate, cool, count directly
Common questions
Why is INAA valued for trace evidence such as glass or gunshot residue?+
Because it needs no chemical dissolution and leaves the sample physically intact, INAA can measure trace elemental composition on the same fragment that later goes to another test, which matters when sample quantity is limited.
What access limitation affects INAA's forensic use today?+
It requires a nuclear reactor for irradiation, so it is only available at a small number of specialised facilities, limiting its routine casework use compared to methods like ICP-MS.
Related terms
- BARC Trombay
- Bhabha Atomic Research Centre, Mumbai. Hosts the Dhruva and Apsara-U research reactors that have historically supplied neutron flux for Indian NAA work.
- Gamma Spectrometry
- Energy-resolving detection of gamma rays. Each radioisotope emits a characteristic gamma at a known energy, which is how NAA identifies elements.
- Half-Life
- The time required for half the radioactive atoms in a sample to decay. Set by the decay constant lambda through t1/2 =...
- HPGe Detector
- A high-purity germanium semiconductor crystal cooled with liquid nitrogen to about 77 kelvin. Resolution at the 1,332 keV gamma line of cobalt-60...
- Neutron Capture (N, Gamma)
- The reaction in which a stable nucleus absorbs a neutron and becomes a radioactive isotope of the same element, emitting a prompt...
- RNAA
- Radiochemical Neutron Activation Analysis. After irradiation, the analyst chemically separates the isotope of interest to remove interfering activity. More sensitive, destructive.
- Thermal Neutron
- A low-energy neutron (around 0.025 eV) that has been slowed by a moderator. The workhorse particle of NAA because slow neutrons are...