CERN Accelerating science

Nuclear Physics

Nuclear Physics

Even if the most commonly known applications of nuclear physics are nuclear power generation and nuclear weapons technology, it is important to highlight that through resarch, nuclear physicists are leading us on a journey of discovery into the nucleus of the atom -the very heart of matter-. The goal is a roadmap of matter that will help unlock the secrets of how the universe is put together. The Nuclear Physics research contribution has impacted our daily life activities by providing applications in many fields, including those in nuclear medicine and magnetic resonance imaging, ion implantation in materials engineering, and radiocarbon dating in geology and archeology.

This quest requires a broad approach to different, but related, scientific frontiers: improving our understanding of the building blocks of matter, discovering the origins of nuclei and identifying the forces that transform matter. To achieve these objectives, leading-edge instrumentation and modern accelerators facilities are required. National laboratories and academic institutions are equipped with such instruments. They drive innovation in scientific instrumentation and have far-reaching impact on research in other fields of science and engineering. From medicine —x-ray and magnetic resonance imaging, radiation therapies for cancer treatment— to materials science —x-ray lithography and neutron scattering— to propulsion and energy production, nuclear physicists have changed our world.

Some of the most relevant facilities, experiments and applications nowadays:

Nuclear spectrometry (incl. radioactive beams, AGATA, GERDA, NUSTAR, FAIR, Spiral2)

Hadron physics (Jefferson lab, PANDA at FAIR)

Heavy ion physics (RHIC, ALICE)

Ion beam accelerators (incl. radioactive beams, AGATA, GERDA, NUSTAR, FAIR, Spiral2)

Spallation sources and research reactors (ILL, ISIS, FRM2, and ESS in a few years)

Nuclear applications (dosimetry, environmental monitoring, cultural heritage)

Hadron (proton and carbon) synchrotron at Med Austron Austria.

 

Detectors in Nuclear Physics

Anger camera module with 15x15 cm2 sensitive area.

Gas-filled detectors: They include Ionization chamber, Proportional counter Multi wire Proportional Chamber, Drift chamber, Time projection chamber, Geiger-Müller tube, Spark chamber.

 

Ionization chamber: The output signal is proportional to the particle energy dissipated in the detector. The measurement of particle energy is possible.

Only strongly ionizing particles (α, protons, fission fragments, or heavy ions) are detected.

Application: Beam monitoring

 

Proportional Counters mode: Charge multiplication takes place and the output signal is proportional to the particle energy deposited in the detector. Measurement of any charged particle is possible.

Applications: Counters, Linear Position Sensitive Detectors and Area Detectors

 

Operation in avalanche (Townsend discharge) mode. The signal is strong and no amplifier is required and their signal is independent of the particle type and its energy.

The Geiger-Müller tube provides information only about the number of particles.

Application: Geiger counter

 

Scintillators detectors: Scintillators materials produce spark or scintillation of light when ionizing radiation passes through them. The operation is in 2 steps:

Absorption of the incident radiation energy and production of the photons.

Amplification of the detected light is generally done by a Photo Multiplier Tubes or  (avalanche) photodiodes

The scintillators used can be divided in 3 groups: inorganic Scintillators, organic Scintillators and gaseous Scintillators.

Anger camera technique

Semiconductor detectors: Solid-state detectors semiconductor detectors and variants including CCDs solid-state track detectors, Cherenkov detector RICH (Ring Imaging Cherenkov Detector)

 

Ge(HPGe, GeLi), Si have a very good energy resolution (for spectroscopy applications) but requires continuous cooling and are therefore bulky and expensive.

CZT and HgI2 are promising since they can operate at room temperature (for Mossbauer spectroscopy for example) with a limited energy resolution.