The suits protect the experiment from dust and other contaminations, which could compromise the result of the experiment.

The suit, together with gloves, mask, overshoes and headphones, is used in order to avoid contamination by particles that we commonly carry in large quantities: only 0.1 grams of dust inside an experimental apparatus with hundreds of tonnes of material can compromise the experiment. In experiments that study rare events it is therefore essential that conditions of extreme purity are maintained.

Protective suit

The purity requirements of all the materials making up the detectors for the LNGS experiments are very stringent. Interactions of neutrinos or dark matter and particular nuclear decays are called "rare events" because the chances are low (see neutrinos or dark matter, double beta decay). . In order to be able to observe these rare events the background "noise" coming from environmental radiations and those emitted by the parts making up the detectors themselves must be minimal. The same applies to contamination inside the experimental apparatuses due to external material. When it is necessary to physically enter the apparatus or to manipulate its elements, a basic precaution is to wear clothing that places a barrier between any polluting particles and an extremely clean environment. A suit is one of these, but gloves, mask, cap and overshoes are also required. Skin, hair, smoke residues, bacteria and dust are all sources of contamination that we carry and lose in microscopic quantities under normal conditions and can be fatal for the success of very sensitive experiments such as those conducted at LNGS. Suffice it to say that even just 0.1 g of dust inside a huge detector like the Borexino detector can compromise results; or that the detectors used in the CUORE and CUPID experiments must be handled in environments protected from direct contact with skin and air containing infinitesimal quantities of radioactive elements (potassium-40 and radon, respectively) that would irreparably interfere with measurements. For some experiments a suit is not enough. Handling of the CUORE detector, for example, takes place inside a special room called the clean chamber. A clean chamber is a contamination-controlled environment, where aeration, ventilation, air filtration, construction materials and operating procedures are regulated to control the concentration and quality of particles in the air.

Fig.1 Assembly of the CUORE detector inside the clean chamber. The components of the detector are handled inside a glove box, a sealed box that allows handling of the pieces in extremely pure conditions.

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