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