VIolation of the Pauli Exclusion Principle · Consequences of Pauli Exclusion Principle (PEP) and spin-statistics connection • No two fermions in the same quantum state • Two
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VIVIolationolation of the of the PPauli auli Exclusion PrincipleExclusion Principle
Catalina Catalina PetrascuPetrascuLNF LNF –– INFNINFN
Commissione III, Torino, 31 Maggio 2004
ContentContent1. Introduction2. The scientific case3. Principle of the experiment4. Preliminary results obtained with a test setup5. The VIP experiment 6. Presentation of the Collaboration and
financial requests
1. Introduction1. Introduction
Preambolo -1Nell’attesa dell’installazione su DAFNE del setup DEAR (febbraio ’99),
la collaborazione aveva previsto un utilizzo dell’apparato per una
ripetizione dell’esperimento di Ramberg e Snow sulla violazione del
Principio di Pauli.
E.Ramberg and G.A.Snow:
"Experimental limit on a small violation of the Pauli principle",
Phys. Lett. B238 (1990) 438.
Installato DEAR, l’idea di verificare il principio di Pauli per gli
elettroni e’ stata portata ugualmente avanti. A Neuchatel, con un
prototipo di apparato equipaggiato con 2 CCD, una misura di
fattibilita’ ha avuto luogo.
La seguenza delle misure e’ questa:
- Febbraio 1999 DEAR installato su DAFNE
- Luglio 1999 inizio della misura principio di Pauli con un prototipo a Neuchatel
- Dicembre 2002, fine presa dati DEAR su DAFNE
- 2004, proposta di utilizzare l’apparato DEAR per Pauli: nuovoesperimento VIP (Violation of the Pauli Exclusion Principle)
Preambolo - 2
2. The scientific case2. The scientific case
The spin-statistics connection
Commutators lead to symmetric wavefunctions and symmetric wavefunctions lead to the Bose-EinsteinStatistics
Anticommutators lead to antisymmetric wavefunctionsand antisymmetric wavefunctions lead to the Fermi-Dirac statistics
The spin-statistics connection
Particles with integer spin obey the Bose-Einsteinstatistics
Particles with half-integer spin obey the Fermi-Dirac statistics
(W. Pauli, Phys. Rev. 58 (1940) 716)
Consequences of Pauli Exclusion Principle (PEP) and spin-statistics connection
• No two fermions in the same quantum state• Two or more bosons may share the same quantum state• Explanation of periodic table of the elements• Solid state theory (e.g. conduction in metals)• Degeneracy pressure maintains stability of white dwarfs (electrons) and neutron stars (neutrons)
• ...
14 Maggio 2004 , Frascati
Seminario di
L.B. Okun
ITEP, Moscow,
Oh if you knew the way that
poems grow
From bits of rubbish, knowing
no shame
(Anna Akhmatova, “Creation”)
“Testing Pauli Exclusion Principle”
Dalle trasparenze di Lev Okun
Spin-statistics connection for elementary particles
- PEP, Lorentz group and CPT: Luders (1954), Pauli (1955);
- SSC in QFT: Pauli (1940, 1950), Luders and Zumino (1958), Wightman (1956 – 1964), Schwinger (1958 – 1961)
- CPT, commuting bosons, anticommuting fermions have positive energy, antiparticles without Dirac sea. Started with Pauli-Weisskopf 1934;
- Greenberg (2004): Lorentz covariance of vacuum matrix elements of time ordered products of fields implies local commutativity.
- All these basic symmetries are questioned at present
There are theories which:
- Theory: push the limit in the region of 10-30 of particular interest: example: the validity of Pauli principle in a higher-dimensional spacetime – small violation in the 3 +1 dimensional; or strings and superstrings etc. –violation of Pauli principle in this range (Mohapatra)
3. 3. Verifica sperimentale Verifica sperimentale del del principioprincipio di Paulidi Pauli
Tests of PEP for electrons
1. Search for non-Paulian atoms, e.g. anomalous Neor anomalous He
2. Search for anomalous X-rays (they signal transitions to anomalous states)
DEAR experience:DEAR experience:
CCDsCCDs excellent detectors for X raysexcellent detectors for X rays
Kaonic Hydrogen measured by DEARKaonic Hydrogen measured by DEAR
-500
0
500
1000
1500
2000
4 5 6 7 8 9 10
X-ray energy (keV)
Coun
ts/60
eV
Tiα
Kα+Fe
Kβ+Khigh
Tiβ
KC Zn
Au
Cr
The best measurementperformed on KaonicHydrogen up to now
Kaonic Hydrogen spectrum after continuous Kaonic Hydrogen spectrum after continuous
background subtractionbackground subtraction
The experiment of Ramberg and Snow (RS)
E. Ramberg and G. A. Snow, Phys. Lett. B238 (1990) 438
Experiment performed in the Muon building at Fermilab with a prototype setup
Detector calibration
Search for anomalous elextronic
transitions in Cu (7.64 keV instead of 8.05 keV) generated bythe transition of one electron (from thecurrent circulated in Cu) from 2p to 1salready filled by 2 electrons
Data analysis in the RS experiment
Expected number of X-rays:
Fraction of “visible” current:
Useful solid angle:
> (1/10) scattering probabilityCapture probability:
Number of scatters just below (in front of) the detector:
Number of “new” electrons: Nnew = 1eI(t)dt
T∫
µDpfmdiamN == ...int
π 8
λ z
NX ≥ 12
β 2NnewN int
10
NX ≥ 12
β 2NnewN int
10I(t)dt
T∫ =15.44 ⋅106 C
D = 0.025 mµ = 3.9 ⋅10−8 mρ = 8.96 ⋅103 kg ⋅m−3
σ =10 m2 ⋅ kg−1
z =1.5 ⋅10−3 m
( ).).%99(107.12/
1090.0262
282
LC
NX
>⋅≤
⋅≥−
−
ββ
4. 4. Risultati del test effettuato a Neuchatel con un prototipo
equipaggiato con 2 CCD
2 CCD setup installed in the basement at Neuchatel
(same principle as R&S)
Measured spectrum
( )272
282
1095.02/
1090.0−
−
⋅≤
⋅≥
ββXN
5. 5. L’esperimento L’esperimento VIPVIP
Actual DEAR setupequipped with 16 CCD 55-30Actual DEAR setupequipped with 16 CCD 55-30
CCD-55 detectors positioning in the cryogenic setup
CCD-55 detectors positioning in the cryogenic setup
K+
CCD mounting,cryogenics andon-cell electronics
CCD mounting,cryogenics andon-cell electronics
Requirements: high compaction to allow optimal shielding and light materials to reduce Bremsstrahlung
- fiberglass frames- cooling system mounted on the top
- thin Al cold finger - reduced diameter of the socket group and, consequently, of the vacuum chamber
Present (April 2004) CCD statusPresent (April 2004) CCD status
Nr. Ti Kα FWHM [eV] err.ccd 1 0 0ccd 2 164.9912 0.5ccd 3 154.609 0.3ccd 4 164.8449 0.6ccd 5 137.6652 0.3ccd 6 175.8235 0.4ccd 7 206.3519 0.6ccd 8 221.9715 0.7ccd 9 152.7059 0.5ccd 10 198.6705 0.8ccd 11 150.4683 0.4ccd 12 227.9897 0.9ccd 13 142.0626 0.4ccd 14 135.5815 0.7ccd 15 138.6213 0.4ccd 16 147.2229 0.5
DEAR setup in the laboratory: visit of Lev Okun
The new “target-cell” – copper bar, spiral –of the VIP experiment
The new “target-cell” – copper bar, spiral –of the VIP experiment
High current, ultra low voltage power supply
CCDs
Thermal insulation 20 µm mylar +1 µm Al
Cooling
Cu CCDs
With respect to test-setup at Neuchatel (duration ~ 3 months):
FWHM (7.6 keV) = 170 – 200 eV => factor 2CCD surface = > factor ~ 30
For 1 + 1 years of DAQ:factor 6 signal
factor 25 backgroundBackground reduction ~ factor 100 (if in Gran Sasso)
(~ 2 counts/day in 1 FWHM at 7.64 keV)
With respect to test-setup at Neuchatel (duration ~ 3 months):
FWHM (7.6 keV) = 170 – 200 eV => factor 2CCD surface = > factor ~ 30
For 1 + 1 years of DAQ:factor 6 signal
factor 25 backgroundBackground reduction ~ factor 100 (if in Gran Sasso)
(~ 2 counts/day in 1 FWHM at 7.64 keV)
302 105.22/ −⋅≤β
6. 6. -- Composizione della CollaborazioneComposizione della Collaborazione-- Piano Piano pluriennalepluriennale didi spesaspesa-- Impegni delle personeImpegni delle persone
VIP CollaborationVIP Collaboration
La collaborazione VIP e’ costituita dai gruppi diFrascati e Vienna della collaborazione DEARcon l’aggiunta del gruppo di Trieste
Piano pluriennale di spesaPiano pluriennale di spesaL’esperimento e’ articolato su 2 anni di presa dati.L’impegno globale di spesa riguarda componenti di vuoto e criogenia,schede di acquisizione e alimentazione, non interamente reperibili fra glispare del laboratorio DEAR.Nell’ipotesi di effettuare l’esperimento al Gran Sasso sono previste spese dimissioni interne.
Piano globale di spesa
4015-5202006
8015405202005
TotaleConsumiInventarioMiss.estero
Miss. interne
Partecipazione INFNPartecipazione INFN
All’esperimento VIP partecipano 7+1? fra ricercatori e tecnologidell’INFN:LNF: Petrascu, Catitti, Guaraldo, Iliescu, D. Sirghi, F. Sirghi, +1?Trieste: Milotti
Per un totale di 2.5-2.8 FTE
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