What Next topic areas
The What Next? Young ones telling the future project is distributed on 5 topic areas – called D.A.R.T.S.
This acronym stands for:
- Detectors ed electronics (D)
- Accelerators e Superconductivity (A)
- Recontruction, data analysis and Computing (R)
- Theoretical and BMS (Beyond Standard Model) physics (T)
- Social and environmental impact (S)
By participating in our initiative you will decide which topic you are the most passionate about or which one you would like to deepen:
Detectors and Electronics
What allows us to “see” the particle is its interaction with a medium. A charged particle loses part of its energy by ionizing the material. This energy is then converted in an electrical signal. There are different ways in which an electrical signal can be induced on an anode to be collected by an electronic system. Not all the detectors are the same!
The detectors answer three main goals: tracking, energy measurements and particle identification. Moreover, the electronics are designed around each specific purpose.
Tracking detectors are located as close as possible to the interaction point and are used to know where the particles are. These detectors can be precise as few microns in the case of the so-called “vertex” detectors.
We use the so-called calorimeters to measure the energy lost by a particle. They can be divided in two categories: electromagnetic and hadronic. The former are typically built out of crystals with a compact design and are used to measure the energy loss of photons and electrons. The latter are composed of layers of active material interspersed by metal to collect hadrons energy information.
Once the momentum and the energy of a particle are obtained, it is possible to complete the identikit with its velocity. To obtain this information, detectors use different techniques: some look for the “time of flight”, which is the time between two interactions between a particle and this detector; other detectors make use of the Cherenkov light emitted when a faster than light charged particle passes through a medium.
In the future we will need new detectors: fast, with high granularity, capable of working at high rates and to cope with high radiation. For the NextGen accelerators, an improvement for the detectors could be presented by a combination of multiple measurements in the same device. We will need trackers with a precise measure of time, high granularity calorimeters to contribute to tracking, or combined ID detectors with double readout calorimeters, that use scintillation together with Cherenkov light information.
Readout electronics follow an independent development: designed on an Application Specific Integrated Circuit (ASIC), these boards are based on miniaturized technologies (down to 28 nm) to guarantee flexibility, velocity and high capability to deal with large amount of data. Moreover, these developments are moving towards a new paradigm, the sharing of space between the detector and the readout electronics, to optimize size and performances.
Accelerators and Superconductivity
Our capability to study the subatomic world depends on the energy at which we make the particles collide. Higher the energy, smaller the structures that we can investigate. This point makes accelerators and their technologies a key part for modern particle physics.
More and more powerful magnets are needed to accelerate particle beams at higher energies towards the wished directions.
The next circular collider is designed to have 100km circumference. It will make use of different acceleration stages. Depending on which particles will be accelerated (fundamentals such as electrons or composite like protons), magnets with different technologies will be used, some of which still needs to be discovered!
Here superconductivity plays a central role. Such technology will minimize current leakages in order to produce particles beams with precise intensity, quality and timing.
Other studies in the accelerator field try to reduce the size of such machines. New technologies such as plasma acceleration (plasma wakefield) induced by electrons or protons allow the accelerated particles to surf on the excited plasma.
Last but not least, innovative studies involve acceleration of particles such as muons. The possibility to collide such particles will push the limits far beyond the present technology.
Reconstruction, Data Analysis and Computing
Signals received from each detector need to be combined to extract useful information. At the beginning of high energy physics this process was performed by looking at photograms, while nowadays we make use of neural networks.
NextGen detectors will use machine learning (e.g., Boosted Decision Tree, BDT, or Artificial Neural Network, ANN) extensively. These techniques are used to search for the right combination of variables to describe events in very problematic conditions (e.g., in the presence of background of a bigger or similar magnitude with respect to the signal).
Other techniques are under development to reconstruct events: Particle Flow algorithms use sub-detectors information to reconstruct single tracks. This is useful in case of tracks really close to each other (namely in case of jets).
Computing already plays a crucial role for accelerators physics: both distributed computing or virtualized cloud systems methods are used by LHC and will become more and more common.
Theoretical Physics and BSM
The Standard Model is the best mathematical tool to describe the interactions in the subatomic world. The Higgs boson represents the missing piece to complete this theory. The reached precision in the theoretical calculations and experimental measurements confirmed that this model is solid. Now, it is necessary to reach new frontiers in order to see if the features described by the Standard Model are properly reproduced in the experimental data.
There are still different experimental and theoretical aspects that need to be answered. The Supersymmetry Model states that for every particle in the Standard Model an equal supersymmetric particle exists. LHC was able to set some limits on the existence of such particles, but only the NextGen colliders will give us the final answer. Other theories postulate that the Higgs boson is not an elementary particle, having a substructure. Theoreticians are the drivers for the future accelerators that will allow us to reach unexplored regions.
Despite the increase in knowledge and the improvement of technology, the dark matter question still remains unsolved. The Weakly Interacting Massive Particles (WIMPs) are good candidates for the “cold” dark matter: with masses and couplings close to the ones of the weak interaction. At the same time, dark photon searches are performed at colliders; this is a boson mediator of a new interaction that could be revealed when the boson itself couples with the ordinary photon. A dark photon could also couple with WIMP-like particles and create a new “dark sector”.
“What’s the point?”, this is the question that almost immediately pops up when we speak of fundamental research. If the first answer we think about is “nothing”, the reason is that some of technological developments are not obvious at the moment of the question. History taught us that science, in particular physics, is full of accidental discoveries, such as penicillin or X rays.
These two examples represent the first pages of a tale of intertwined destinies between fundamental research and public welfare. Small accelerators machines have already opened the gates to powerful diagnostic devices: the Positron Emission Tomography (PET) is a medical imaging technique based on the reconstruction of two photons produced by the annihilation of a positron from a radioisotope (injected in a patient’s body) and an atom electron (of the patient).
One of the latest developments is the hadron-therapy, that uses the knowledge of particles beams to treat tumours reducing the damage caused to the healthy biological tissues.
INFN is a world renowned expert with CNAO (Centro Nazionale di Adroterapia Oncologica), a centre specialized in hadron-therapy in Pavia, and the project CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) located at Laboratori Nazionali del Sud in Catania, one of the few world sites where it is possible to treat eye tumour with particles beams.
Moreover, we cannot forget the World Wide Web, born at CERN to help scientists to share data and information.
The future projects are civil engineering and environmental challenges. It is of the utmost importance to take into account the impact of these on the surrounding landscape; the energy needed to keep them functioning; and the usage of environmentally safe materials.
Finally, it is important to remember that fundamental research answers even more deep questions. It paves the way towards knowledge, bolstering the curiosity that makes us free.
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