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Vacuum birefringence and dichroism signals in the PVLAS experiment Ugo Gastaldi, INFN-LNL Legnaro on behalf of the PVLAS Collaboration ICHEP’06 Moscow 27- 07- 2006. Introduction DYCHROISM PRL96,110406(2006) vacuum B induced rotation
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Vacuum birefringence and dichroism signals in the PVLAS experimentUgo Gastaldi, INFN-LNL Legnaro on behalf of the PVLAS CollaborationICHEP’06 Moscow 27- 07- 2006 • Introduction DYCHROISM PRL96,110406(2006) vacuum B induced rotation BIREFRINGENCE QCD-06 and ICHEP-06 vacuum B induced ellipticity • Ellipticity measurements PHASE and AMPLITUDE calibrations with gases VACUUM Measurements • Outcome VACUUM BIREFRINGENCE has OPPOSITE SIGN of He, Ne,… Birefringence m=0.8-1.8meV M=1-7 10+5GeV 0++ boson responsible??? • Prospects CONFIRM LIGHT BOSON INTERPRETATION by REGENERATION measurements REDUCE NOISE INCREASE DUTY CYCLE PRECISE MEASUREMENTS OF m by changing magnet length
PVLAS Collaboration (Trieste, Pisa, Legnaro, Frascati, Ferrara): from left to right E.Polacco, E.Milotti, E.Zavattini, R.Cimino, G.Cantatore, S.Marigo, U.Gastaldi, G.Petrucci and A.Zanetti standing G.Zavattini, M.Karuza, G.Ruoso, G.DiDomenico and F.DellaValle seated (S.Carusotto, G.Raiteri and P.Temnikov are not in the picture)
PVLAS EXPERIMENT • SITE • MAGNET • ELLIPSOMETER • Fabry-Perot CAVITY • MODULATIONS • FINESSE • ELLIPTICITY • CONTROLS • OPERATIONS
PVLAS site: two opposite walls of the square pit support the concrete beam (with turntable and cryostat on top)pit floor and pit walls rest on separate foundations
PVLAS top optical bench resting on 4 granite pillars thatsurround the (rotating) cryostat (with superconducting magnet inside)
PVLAS: Vacuum, N2 and Ne ellipticity phases of 2004-2005 runs
PVLAS 1064nm light ISOELLIPTICITY and ISOROTATION curves in (m,M) plane
Physics outcome DICHROISM(IR) amplitude circa 4 10-12(published in PRL2006) ELLIPTICITY(IR) amplitude circa 2-5 10-12, phase opposite to CME(He, Ne) ELLIPTICITY(Gr) amplitude amplitude circa 3-15 10-12, phase opposite to CME(He, Ne) If effects observed truly generated mostly by quantum vacuum effects and not by apparatus If microscopic interpretation in terms of existence of ultralight bosons coupled to two photons valid If ultralight bosons have spin zero and only one sort present Phase opposite to CME(noble gases) tells bosons are scalars 0++ m=0.8-1.8 meV M=0.1-0.7 10+5 GeV
PVLAS oasis in desert of (m,1/M) planemain question:oasis or mirage???
PROSPECTS Confirm LIGHT BOSON interpretation regeneration measurements (in parallel to polarization measur.s) with permanent magnet (beeing purchased to be installed below ellipsometer) Reduce NOISE AMAGNETIC ACCESS STRUCTURE beeing installed PERMANENT MAGNETS planned in place of superconducting m. (no rotating stray field on FP mirrors and other optics elements) Improve SIGNAL Increase DUTY CICLE with permanent magnets (no cryo. constraints) Measure m accurately by changing length L of magnetized volume (in polarization and regeneration measurements)
PVLASafter June 2006 removal of Fe access structure around the vertical granite supportof the top optical bench,that surrounds the cryostat
W=20 mwatt out of FP N=5 10+4 in FP, give 5 10+21 photons sec-1passing through PVLAS magnet C=16 10-12conversion probabilityin PVLAS magnet 1m long 5.5 Tesla8 10+10 bosons sec-1boson beamsR=16/(4x7.5) 10-12reconversion prob.in permanent magnet0.5m long 2 Teslaexpect4 10-2 photons sec-1regenerated in perm. mag
PVLAS superconducting Morpurgo magnet(assembled with vertical bore)before insertion intowarm bore cryostat
Run 1091_1VacuumSOM 90B=4.35 Tesla Run 1092_0_2VacuumSOM 90B=0 Tesla
Run1091_0SOM 90 Run1084_0 SOM 0
References Iacopini and Zavattini PL85B(1979)151 Maiani, Petronzio and Zavattini PL B175(1986)359 Raffelt and Stodolsky PR D37 (1988)1237 Cameron et al. (BFST Collab.) PR D47(1993)3707 Rizzo et al. IRPC 16 (1997) 81 and refs. therein Zavattini et al (PVLAS Collab.) PRL 96(2006)110406 Gastaldi arXiv:hep-ex/0605072 (2006) and refs. therein
B dependence:Oct. 2004, Ne 18mbar 2 ωM peak 1 ωM peak B4 B2 B2
PVLAS532nm and 1024nm light ISOELLIPTICITY curves in (m,M) plane
PVLAS 532 nmlight ISOELLIPTICITY and ISOROTATION curves in (m,M) plane
PVLAS532nm and 1024nm light ISOROTATION curves in (m,M) plane
Regeneration scheme with TWO identical OPPOSITE GOING boson beams
Regeneration scheme with TWO identical OPPOSITE GOING boson beams