Suite du séminaire CPPM 5/12/2011 Morceau choisi de : FLOWER Fluctuations of the Light velOcity...
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Transcript of Suite du séminaire CPPM 5/12/2011 Morceau choisi de : FLOWER Fluctuations of the Light velOcity...
suite du séminaire CPPM 5/12/2011Morceau choisi de :
FLOWERFluctuations of the Light velOcity WhatEver the Reason
François Couchot, Xavier Sarazin, Marcel UrbanLAL Orsay
Jérome Degert, Eric Freysz, Jean Oberlé, Marc TondussonLOMA, Bordeaux
Presented by Xavier Sarazin9èmes Journées Phénomènes Ultra-rapides
Université de Rouen17-19 Octobre 2011
Vacuum LengthL (pc)
Tim
e W
idth
rm
s (s
)
Pulsar ~kpcFWHM ~ s
GRB ~ 1-10 GpcFWHM ~ 10 ms
as )(50t mL
We can improve the sensitivity using femto laser
100 fpc = 3 kmFWHM ~ 6 fs
Measurements of possible fluctuations of c
The FLOWER Setup
Primary pulse
COLA (LOMA)Ti:SapphirePulsed Laser10 nJ / pulse
t0 (rms) ~ 20 fs(rms) ~ 15 nm
Motorstage
Diode
Non linearcrystal
Intensity Autocorrelation
RC = 1.8 mConcave Mirror M2Planar Mirror M1
M
The length of the cavitycan be modified
The number of round tripscan be modified
Input/output Hole
The number of round trips can be modified
Allow measurements of different vacuum path lengths Lvacuum
For a given number of round trips, the length of the cavity can be modified
The systematic due to possible mirror dispersions can be separately measured
We will first validate and calibrate the setup by filling the Herriot cell with a gas
chromatic dispersion (Argon@1 atm, L=50m,=80015nm) ~ 60 fs
General solution = k./ N N = number of round trips
RC = 1.8 mLength (m) of the Herriot cell
(r
ad)
Example with 5 round trips
Preliminary Tests in LOMA
Gold metallic concave mirror already available“Ultra high” quality
= 15 cm
Preliminar planar mirror Dedicated high quality mirror with a
hole has been purchased
Here an example with 11 round trips
Preliminary simulation for 21 round trips and RC = 1.8 m
Stable solution for = 16/21 and L = 1.56 m
By construction: the outgoing beam is similar to the incoming beam
With the available gold concave mirror, we can already reach a vacuum path length
Lvacuum = 2×21×1.56 = 65.5 meters
Flower Phase 1Herriot cell Lcell ~1.55 m Can reach at least Lvacuum = 65 m with 21 round trips
Width (rms) of COLA laser pulses ~ 20 fs
Accuracy autocorrelation measurement ~ 2 fs (width rms)
Expected sensitivity of vacuum fluctuations: 0 ~ 1 fs.m1/2
0 ~ 0.2 fs.m1/2Better than GRBSimilar to microburst from Crab pulsar
With fastest femto laser: rms ~ 2 fs
Improved accuracy of autocorrelation meas. ~ 0.5 fs (150 nm step)
Flower Phase 2
This setup allows to measure the dispersion in gas with high accuracy
Test if any discontinuity or discrete properties of the photon propagation in vacuum
Super-Flower
Herriot cell Lcell ~ 50 m (as CALVA in LAL Orsay)
~ 50 round trips
Can reach Lvacuum = 5 km
If 0 ~ 50 as.m1/2,
Width (rms) of initial laser pulses in~ 2 fs
in~ 2 fsvacuum ~ 3.5 fs
Lvacuum=5 kmout~ 4 fs
Effet SHADOK
s s
Virtual fermion
antifermion pair1810.31
msN
ciii
The idle pulse, circularly polarized +1, moves with a velocity c
A pump laser, circularly polarized +1, with ultra high intensity, masks some virtual pairs
Number of occupied pairs ii NNN
The idle pulse (circularly polarized +1) will move with a higher velocity c*
eiiii NN
c
NNc
64/1
1*
)/(10.264
341 mphotonsNN
N
c
c
e
Effet SHADOK
If the laser spots are focused along 1mm,
it should creates an advance of the idle pulse of 1 fs
Mercury Laser @ Livermore (LLNL)• 1 PW peak power: 15 J, 15 fs• 1023 W/cm2 maximum focused irradiance• 10 Hz repetition rate• 1 m
If focal spot ~ 1m2 c/c ~ 3.104
A mechanism has been proposed to give a finite value of the speed of light in agreement
with the observed value
This quantum vacuum description gives also the origin of and
It leads to two experimental predictions
possible fluctuations of the transit time of photons of ~ 50 as.m
a possible advance of a idle pulse of ~ 1 fs after having propagated 1 mm in a ultra
high intensity pump laser
Ultra short femto lasers seem to be the ideal tool to perform these tests
Attosecond pulses for FLOWER ?
Are FROG/RABBIT able to detect a time broadening of the XUV attosecond pulses ?
(see S. De Rossi’s talk for geometric aberrations)
CONCLUSIONS