165,635 research outputs found
Application of photon detectors in the VIP2 experiment to test the Pauli Exclusion Principle
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 1s transitions in copper, where 2
electrons are in the 1s 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 . 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
VIP 2: Experimental tests of the Pauli Exclusion Principle for electrons
The Pauli Exclusion Principle (PEP) was famously discovered in 1925 by the
austrian physicist Wolfgang Pauli. Since then, it underwent several
experimental tests. Starting in 2006, the VIP (Violation of the Pauli
Principle) experiment looked for 2p to 1s X-ray transitions in copper, where 2
electrons are present in the 1s state before the transition happens. These
transitions violate the PEP, and the lack of detection of the corresponding
X-ray photons lead to a preliminary upper limit for the violation of the PEP of
4.7 * 10^(-29). The follow-up experiment VIP 2 is currently in the testing
phase and will be transported to its final destination, the underground
laboratory of Gran Sasso in Italy, in autumn 2015. Several improvements
compared to its predecessor like the use of new X-ray detectors and active
shielding from background gives rise to a goal for the improvement of the upper
limit of the probability for the violation of the Pauli Exclusion Principle of
2 orders of magnitude
Searches for the Violation of Pauli Exclusion Principle at LNGS in VIP(-2) experiment
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 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 set by the VIP experiment. With
upgraded detectors for high precision X-ray spectroscopy, the VIP-2 experiment
will improve the sensitivity by two orders of magnitude.Comment: 5 pages, 3 figures, 1 table. Conference proceedings for oral
presentation at TAUP 2015, Torin
New experimental limit on the Pauli Exclusion Principle violation by electrons
The Pauli Exclusion Principle (PEP) is one of the basic principles of modern
physics and, even if there are no compelling reasons to doubt its validity, it
is still debated today because an intuitive, elementary explanation is still
missing, and because of its unique stand among the basic symmetries of physics.
The present paper reports a new limit on the probability that PEP is violated
by electrons, in a search for a shifted K line in copper: the presence
of this line in the soft X-ray copper fluorescence would signal a transition to
a ground state already occupied by 2 electrons. The obtained value, , improves the existing limit by almost two
orders of magnitude.Comment: submitted to Phys. Lett.
Population Estimates, 2010-2015, DVRPC's 28-County Extended Data Services Area
As the Greater Philadelphia region's metropolitan planning organization (MPO), the Delaware Valley Regional Planning Commission (DVRPC) provides technical assistance and services to its member state, county, and local governments; the private sector; and the public. Delaware Valley Data is our periodic series of free data bulletins, data snapshots, and analytical reports. Data Bulletin #097 provides county- and subcounty-level population estimates as of July 1, 2015, for the 28 counties located within DVRPC's extended data services area, released by the U.S Census Bureau in May 2016. The Census Bureau's Population Estimates Program (PEP) produces July 1st estimates for the years following the last published decennial census and, in most cases, simultaneously revises annual estimates released in previous years. Existing data series such as births, deaths, federal tax returns, Medicare enrollment, and immigration are used to update the base counts from the decennial census. PEP estimates are used in federal funding allocations, in setting the levels of national surveys, and for monitoring recent demographic changes
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