The Pauli Exclusion Principle (PEP) was introduced by the austrian physicist Wolfgang Pauli in 1925. Since then, several experiments have checked its validity. From 2006 until 2010, the VIP ...(Violation of the Pauli Principle) experiment took data at the LNGS underground laboratory to test the PEP. This experiment looked for electronic 2p to Is transitions in copper, where 2 electrons are in the Is state before the transition happens. These transitions violate the PEP. The lack of detection of X-ray photons coming from these transitions resulted in a preliminary upper limit for the violation of the PEP of 4.7 × 10-29. Currently, the successor experiment VIP2 is under preparation. The main improvements are, on one side, the use of Silicon Drift Detectors (SDDs) as X-ray photon detectors. On the other side an active shielding is implemented, which consists of plastic scintillator bars read by Silicon Photomultipliers (SiPMs). The employment of these detectors will improve the upper limit for the violation of the PEP by around 2 orders of magnitude.
IntroductionThe success of radiotherapy depends on the ability to inhibit tumour growth, and relapse after therapy is determined by cells that retain their clonogenic potential. The radiation ...sensitivity of isolated tumour cell clones in vitro is routinely determined with clonogenic assays. In solid tumours, however, clonogenic cells are not isolated and we carried out experiments to measure the influences of cell-cell contact on their proliferative potential. To this end we developed a new experimental approach to measure the effects of radiation on tumour cell populations. The observations can be understood with the help of a novel stochastic model with a well-defined biological basis.Material and methodsT47D cells (human breast carcinoma) were grown at various concentrations in F(flat)-bottom and V-bottom wells of 96-well culture plates. The spheroid outgrowth method was also used to obtain densely-packed tissue cell cultures. A Gammacell40 irradiator equipped with a 137Cs source was used to treat cell cultures. Cell fusion was assessed by confocal microscopy. Syncytin 1 expression was assessed by RT-PCR and by flow cytometry using an anti-HERV antibody (clone ab7115, Abcam).Results and discussionsThe probability of cell survival after 8 Gy radiation treatment increased ~4.7 times when the cells were grown in V-bottom wells as compared to cells grown in F-bottom wells (p(survival)=0.0113 and 0.0024, respectively). Microscopic inspections of tissue-like cultures showed that after treatment cell populations were mostly composed of giant cells with multiple nuclei. Cytoplasmic bridges joining different cells were clearly visible. Giant cells and cytoplasmic bridges disappeared at later times (>600 hours) when the cells displayed normal morphology and started to proliferate again. Sequence analysis of cloned RT-PCR products showed that cells expressed a Syncytin 1 homologous protein (Sp). Flow cytometry assays confirmed cytoplasmic expression of Sp and revealed that Sp translocated to the cell surface of irradiated cells committed to death. The fraction of cells surviving 8 Gy treatment was significantly reduced in cultures treated with anti-Sp antibodies.ConclusionOur experimental findings indicate that recovery of breast tumours from radiation is very likely to involve complex pathways that act at the cell population level and that include events of cell fusion mediated by a protein homologous to Syncytin 1.
Nonlinear effects in vacuum have been predicted but never observed yet directly. The PVLAS collaboration has long been working on an apparatus aimed at detecting such effects by measuring vacuum ...magnetic birefringence. Unfortunately the sensitivity has been affected by unaccounted noise and systematics since the beginning. A new small prototype ellipsometer has been designed and characterized at the Department of Physics of the University of Ferrara, Italy entirely mounted on a single seismically isolated optical bench. With a finesse
F
=
414,000 and a cavity length
L
=
0.5
m we have reached the sensitivity of
ψ
=
2
⋅
10
−
8
1
/
Hz
given the laser power at the output of the ellipsometer of
P
=
24
mW. This record result, very close to the predicted limit, demonstrates the feasibility of reaching such sensitivities, and opens the way to designing a dedicated apparatus for a first detection of vacuum magnetic birefringence.
In the VIP (VIolation of Pauli exclusion principle) and its follow-up VIP- 2 experiments at the Laboratori Nazionali del Gran Sasso, we test the validity of the Pauli Exclusion Principle, by ...searching for x-rays from copper atomic transitions from a 2p orbit electron to the ground state which is already occupied by two electrons. Such transitions are prohibited by the Pauli Exclusion Principle. The physics run of the VIP-2 experiment started in late 2016 and will collect data for three years. From the first data taking period of two months we have obtained a new limit better than the VIP result from three years of running. In this article we present the published first physics result from the VIP-2 experiment and discuss about the future perspectives.
The VIP (Violation of Pauli exclusion principle) experiment and its follow-up experiment VIP-2 at the Laboratori Nazionali del Gran Sasso (LNGS) search for X-rays from Cu atomic states that are ...prohibited by the Pauli Exclusion Principle (PEP). The candidate events, if they exist, will originate from the transition of a 2p orbit electron to the ground state which is already occupied by two electrons. The present limit on the probability for PEP violation for electron is 4.7 ×10-29 set by the VIP experiment. With upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment will improve the sensitivity by 2 orders of magnitude.
We are experimentally investigating possible violations of standard quantum mechanics predictions in the Gran Sasso underground laboratory in Italy. We test with high precision the Pauli Exclusion ...Principle and the collapse of the wave function (collapse models). We present our method of searching for possible small violations of the Pauli Exclusion Principle (PEP) for electrons, through the search for "anomalous" X-ray transitions in copper atoms. These transitions are produced by "new" electrons (brought inside the copper bar by circulating current) which can have the possibility to undergo Pauli-forbidden transition to the 1s level already occupied by two electrons. We describe the VIP2 (VIolation of the Pauli Exclusion Principle) experimental data taking at the Gran Sasso underground laboratories. The goal of VIP2 is to test the PEP for electrons in agreement with the Messiah-Greenberg superselection rule with unprecedented accuracy, down to a limit in the probability that PEP is violated at the level of 10−31. We show preliminary experimental results and discuss implications of a possible violation.
By performing X-rays measurements in the "cosmic silence" of the underground laboratory of Gran Sasso, LNGS-INFN, we test a basic principle of quantum mechanics: the Pauli Exclusion Principle (PEP), ...for electrons. We present the achieved results of the VIP experiment and the ongoing VIP2 measurement aiming to gain two orders of magnitude improvement in testing PEP. We also use a similar experimental technique to search for radiation (X and gamma) predicted by continuous spontaneous localization models, which aim to solve the "measurement problem".
Introduction The Abdus Salam International Centre for Theoretical Physics (ICTP) and the Trieste University have initiated in 2014 a Master of Advanced Studies in Medical Physics a two-years training ...programme in Medical Physics. The programme is designated to provide young promising graduates in physics, mainly from developing countries, with a post-graduated theoretical and clinical training suitable to be recognised as Clinical Medical Physicist in their countries. Presently, the 3 cycles of the programme has seen 49 participants from 33 Countries: Africa (19), Asia (11), Central and South America (14), and Europe (5), selected from more than 400 applicants per year. Scholarships are awarded to candidates from developing countries with support of the IAEA, TWAS, KFAS, IOMP, EFOMP and ICTP. Material and methods The programme is developed following the recommendations of IOMP and IAEA for education and clinical training. In the first year 332 lectures and 228 h of exercises are devoted to all main fields of medical physics. The second year is spent in one of the 12 medical physics department of the hospitals’ network for the clinical training in: radiation oncology or diagnostic and nuclear medicine, on a programme developed adapting the IAEA (TCS37, TCS47 and TCS50) and AFRA guidelines. Conclusions IOMP, EFOMP and IAEA are seeing this initiative as an answer to the growing demand of Medical Physicists in developing Countries, representing an important European contribution to the development of medical physics in the developing world.
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