Microcosm with a View

A journey into a world where the rules are not always those of common sense. More than a museum, "Microcosm" is a permanent exhibition

Camera a NebbiaSistema Museale Università di Parma

The exhibition "Micorocosm with a view" organized by the Physics Department of the University of Parma in collaboration with the National Institute of Nuclear Physics (INFN), with the European Center for Nuclear Research (CERN) in Geneva and with the Institute of Materials for Electronics and Magnetism (IMEM). They are actual working tools that show events in real time.

Camera a NebbiaSistema Museale Università di Parma

The Wilson Chamber or diffusion cloud chamber of "Microcosm with a view" allows the continuous detection of the particles passing through its sensitive volume.

Camera a NebbiaSistema Museale Università di Parma

Operation of the Fog Chamber

The camera allows you to view the traces of electrically charged particles (ions) on which drops of alcohol condense and appear as a trail. For this to happen, the vapor must be supersaturated, that is, ready to form fog. This condition occurs near the black plate on the bottom of the chamber cooled to about -30° C, where the vapor that diffuses from above is found to be supersaturated thus forming a visible trace of droplets.

Giuseppe Occhialini e Patrick BlackettSistema Museale Università di Parma

In England in 1931 at the prestigious Cavendish Laboratory, directed by Lord Ernest Rutheford, Patrick Blackett and Giuseppe Occhialini, they studied cosmic rays with the use of the cloud chamber.

Particelle ionizzate dalla radiazione cosmicaSistema Museale Università di Parma

Types of particles

The cloud chamber allows you to view various types of particles such as alpha particles (which produce short and rather large traces), electrons (thin traces that can be straight or curved and that can cross the entire chamber), muons that is particles produced by cosmic radiation (which generate straight and clearly visible traces).

Camera a NebbiaSistema Museale Università di Parma

particolareSistema Museale Università di Parma

Photoelectric effect

The instrument consists of a lamp, source of the light radiation, and a metal sheet connected to an electroscope. The emission of electrons from the metal foil causes the foil to be positively charged. The electroscope detects this charge.

apparato per esperimento effetto fotoelettricoSistema Museale Università di Parma

apparato per esperimento effetto fotoelettricoSistema Museale Università di Parma

Apparato per diffrazioneSistema Museale Università di Parma

Light: electromagnetic wave

The electron diffraction experiment allows us to observe the wave nature of the particles (waves of matter).

Effetto diffrazioneSistema Museale Università di Parma

Sfera al plasmaSistema Museale Università di Parma

Plasma sphere

The light streaks inside the sphere are generated by electrons accelerating from the center outwards. The electrons hitting the gas atoms inside the sphere cause light to be emitted as an effect of the electrons falling back after the collision in the atomic orbits allowed to them. increase the potential difference resulting in a higher concentration of the light strips.

Camera a ScintilleSistema Museale Università di Parma

The Spark Chamber is an instrument for the detection of charged elementary particles. This chamber allows you to observe Cosmic Rays.

RadiometroSistema Museale Università di Parma


The operating principle of this device is based on the different absorbing behavior of the white surfaces compared to the black ones. The molecules of the gas are in fact hit by the photons of the electromagnetic radiation and move with speed proportional to the energy of the photons of the incident radiation. The black faces of the radiometer absorb the shocks of the molecules while the white faces repel the molecules themselves. The energetic imbalance between the two surfaces causes the faces to rotate.

Misura della velocità del suonoSistema Museale Università di Parma

The Speed of Sound

The experiment allows you to measure the speed of sound in the air. The rolls of pipes are 50 m long, can be connected together. Just bring one of the two ends close to the mouth and the other to the ear: by emitting any short-lasting sound our ear will perceive a delay.With a sensor it is possible to make a more precise measurement and from the equation speed = space / time derive value of the speed of sound.

AerogelSistema Museale Università di Parma

The Airgel material is essentially composed of silicon like glass, in which, however, the empty spaces make up 99.9% of the volume and compared to glass, it is up to seven hundred times less dense.

AerogelSistema Museale Università di Parma


Discovered in the late 1960s, the Aerogel material has several applications. It is used as a thermal insulator especially in aeronautics (due to its very light weight) and to absorb sounds. Aerogel is used in particle detectors called RICH (acronym for Ring Imaging Cherenkov), which can identify the mass of particles based on the Cherenkov radiation that a charged particle produces precisely by passing through matter. Cherenkov light is emitted when the speed of the charged particle is greater than the speed of light in that material. The ratio of the two speeds determines the angle of emission of this light relative to the direction of the particle. If the material is highly transparent, and the Aerogel is, the light emitted can be collected on a plane. The angle of light emission depends on the mass and speed of the particle in question. It is therefore the physics observable that allows us to trace the mass of the particle.

Tubo di CrookesSistema Museale Università di Parma

Crookes' cathode ray tube

The Crookes cathode ray tube is a glass tube containing rarefied gas at a pressure of about one hundred thousandth of atmospheric pressure. Inside there are two metal electrodes with a high voltage difference (a few thousand volts). Electrons are emitted from the cathode as a result of the bombardment of gas ions accelerated by the applied voltage. Along the electron beam there is a Maltese cross-shaped obstacle whose shadow is seen on the screen as a lack of greenish light. This light (fluorescence) is produced when electrons bombard this type of glass. Electrons behave like a beam of light even if with other experiments it has been seen that they are particles with mass and electric charge. Like all electric charges in motion, electrons are also deflected by a magnetic field as can be easily observed by approaching the magnet to the tube.

Credits: All media
The story featured may in some cases have been created by an independent third party and may not always represent the views of the institutions, listed below, who have supplied the content.
Explore more
Related theme
Parma 2020+21
Discover the excellence Italian Capital of Culture
View theme
Google apps