An]-‐atomi freddi: prospe[ve future

An#-­‐atomi freddi: prospe2ve future
Gemma Testera INFN Genova An#-­‐atomi
p e+
An1proton-­‐ positron An1-­‐Hydrogen CERN: 5 Interna1onal collabora1ons about 100 Ins11te Now INFN (comm3) -­‐AEgIS -­‐ASACUSA (1998-­‐2007 ATHENA) − +
Positronium a
) A
. M
ills (
Univ. C
alifornia R
iverside) e e
b) S. Hogan &S. Cassidy UCL London c) P. Crivelli et al, (ETH-­‐ Zurigo) d) Tokyo University e) …. f) AEgIS : An1H formato vai scambio carica con Ps Rydberg µ +e−
Muonium a) K. Kirch (ETH-­‐ PSI) Physics goal (an#H)
What Next: •  molto chiaro l’obie]vo di fisica •  il problema non e’ cosa misurare •  ma come preparare gli an1-­‐atomi nella giusta condizione iniziale Obie]vi : spearoscopia an1H 1S-­‐2S Test CPT per barioni, sensibilita’ potenziale 10-­‐13 (o anche molto maggiore 10-­‐18 ) GSHFS Δg
≈ 10 −6 − 10 −8 o superiori Principio Equivalenza: Interferometria (an1) atomica: sensibilita’ g
Il percorso: 1.  sviluppi tecnologici e sperimentali 2.  tecnicamente possibili 3.  richiedono inves1mento di lavoro ( e di denaro) 4.  competenze di fisica atomica integrate con competenze presen1 entro INFN 5.  gruppi concorren1 su AD lo stanno facendo Adapted from J. Tasson WAG 2013 J. Tasson PRD 2011 li an#-­‐atomi per ora non sono freddi come i atomi……
uesto dipende dal faao che an1H deve essere formato a par1re dai cos1tuen1 carichi M. Amore] et al. (ATHENA Collabora1on) NATURE 419 (2002) 456 Produc1on and detec1on of cold an1hydrogen atoms Grande contributo INFN Hbar Temperature: 10-­‐100 K Typical: 104 pbar 7107 e+ every 300 sec 17% of the pbars are converted in An1H (2000 an1H/cycle cioe’ ogni 300 sec) Also ATRAP Phys. Rev. Lea. 89 (2002) 213401 How cold the an#H should be?
It also depends on how many an1-­‐atoms are available… Trapping in magne1c traps : Max well depth few hundred mK Spectroscopy (high precision, compe11ve with Hydrogen): mK or below Gravity measurement : AegIS @100mK 1% (target goal, not yet reached) An1H interferometry : mK or µK 2 strategies toward ultracold an#H
1)  Cool as much as possible the ingredients before forma1on 2)  Cool an1H once is formed (Laser cooling, collisions(?)) plus combina1on of the two strategies 3)  Form Hbar+ cool it and detach the extra positrons (GBAR experiment) AEer forma#on
1)  Trap an1H in a magne1c trap 2)  Form a cold beam p e+ e+
Traps (Penning or Malmberg)
1
EC =
4πε 0 r
1
r =
3 n
e
Pbars and positrons available with high energy (MeV) Trapping in ion traps Cooling Manipula1on ( shaping the density…) 3 regimes 1)  Single par1cles EC
Γ=
K BT
2)  Many par1cles: plasma like a gas 3)  Many par1cles, very cold Coulomb crystal Γ << 1
Γ >> 1
Hbar forma#on
1) 2) *
p+e +e = H +e
+
+
*
+
*
p + Ps → H + e −
La reazione 2 e’ quella che permeaera’ di formare Hbar ultrafreddo 3 body recombina#on
p + e+ + e+ = H * + e+
e+ Temperature : few K -­‐ 10 K 1H in high n states rge spread n distribu1on Pbar injected into the e+ plasma Slowing down+ recombina1on ! !
= − µ ⋅ B = ± µB
! ! !
!
= ∇( µ ⋅ B) = ∓ µ∇B
ALPHA 2013 Surround the nested trap with a trap for neutral an1H Magne1c gradient: trap an1H Trap depth for neutral: few hundreds mK ALPHA: 4 trapped an=-­‐atoms/hour -­‐An1H is not cold enough: trapped the tail of the energy distribu1on -­‐An1H is not cold beacuse recombina1on happens before complete thermaliza1on of pbars by collisions with e+ H produc#on by charge exchange 1) Catch pbar from AD (CERN), cool, store
Pbar ultracooling: 100 mK (10 µeV)
Do not move pbars during recombina#on
n AEgIS now)
2) Accumulate e+;
3) Form Ps Launch e+ toward a e+ to Ps
converter (nanoPorous target);
3) Excite Ps to Rydberg states
(laser pulses)
4) Produce Rydberg Hbar: pulsed produc#on
*
p + Ps * → H + e −
5) Form the beam (electric field gradient) 6) Measure gravity using a moiré deflectometer and a #me-­‐posi#on
sensi#ve detector 1% with about 1000 atoms
Also ATRAP but using a different scheme to ma
ooling trapped an#protons before Hbar forma#on
Trap pbars with electrons in Penning like trap cool electrons via radia1on (need high B) quantum limit@ cool axial mo1on of electrons by coupling it to a LC tuned circuit Toward sub-­‐Kelvin resis=ve cooling and non destruc=ve detec=on of trapped non-­‐neutral electron
S. Di Domizio, D. Krasnický, V. Lagomarsino, G. Testera, R. Vaccarone and S. Zavatarelli JINST 2015 JINST 10 P01009 Direct cool of pbars with tuned circuit …..Hard to go below hundreds mK vapora1ve cooling and/ or adiaba1c cooling: demonstrated by ALPHA and ATRAP: Kelvin ollisions of an=protons with nega=ve ions or molecules laser cooled and trapped with them Nega1ve ions: work in progress@Heidelberg (A. Kellerbauer et al.) Os-­‐ La-­‐ Nega1ve molecules: D. Comparat (AEgIS) talk@TCP2014 C2-­‐ Limit temperature: range of µK Adapted from D. Comparat TCP2014 emperature and total kine#c energy of trapped n#protons
Il plasma ruota a causa del campo elearico dovuto alla carica spaziale e il campo magne1co La temperatura e’ definita nel sistema di rif rotante L’energia cine1ca dovuta alla rotazione c’e’ anche a T=0 La energia cine1ca con cui si forma an1H e’ dominata dalla rotazione del plasma per T<100 mK con N=105 trapped par1cles Plasmi a T-­‐> 0 o Cristalli di Coulomb in trap Penning non sono fermi gole o poche par1celle si concentrano vicino all’asse dove questo effeao puo’ essere reso piccolo Problema simile nel caso di RF trap (no B) Linear RF trap, no B Moto secolare+ micromoto Temperatura: energia del moto secolare Micromoto: ha energia che dipende dalla distanza dall’asse Con plasma o Coulomb Plasmi a T-­‐>0 o Cristalli di Coulomb in trap RF non sono fermi Fondamentale differenza tra cooling di par1celle cariche e atomi neutri Penning-­‐Malmberg trap Cooling di An#protoni con ioni nega#vi (o molecole) laser cooled: regime di lavoro con pochi an#protoni alla volta • 
• 
• 
• 
• 
• 
Immagine (con fluorescenza) di ioni intrapp
Raffredda1 con laser Regime di cristallizazione I piu’ leggeri vanno al centro Formano una stringa sull’asse Non c’e’ extra energia oltre la temperatura
ositrons and Positronium
We need Ps with velocity below 104 -­‐105 m/s Must be excited n= 18-­‐20 Cross sec1on increases at low velocity Needs Ps as slow as possible Ops 142 sec life1me If too slow it stays too close to the target Isotropic or direc1onal emission (?) Now in AEgIS: target close to pbar Rydberg Ps atoms fly toward Pbar Huge inefficiencies due to solid angle Energy of the emiaed Ps depends -­‐  Pore size -­‐  Target temperature -­‐  Implanta1on depth (number of collision) Target at 50 K: a significant frac1on emerge with 50 K
5 104 m/s S. Mariazzi et al., Phys. Rev. Lett. 104, 243401 (2010). ser cooling of Ps before excita#on to Rydberg states
e+ 2P 3.2 ns, 100 µsec annihila1on 243 nm 1S E. Liang Op1cs Comm. 65 (6) 1988 (419) H. Iijima et al. Journ. Phys. Soc. Japan 70 11 (2
NIMA 455 (2000) 104 vrecoil =
hk 1
2π mPs
=1.5 103 m/s Recoil limit= 0.1K It is enough to scaaer 30 photons to get a significant collima1on!! 4 lasers, radial cooling An1H forma1on Ps + Rydberg excita1on Ps* Cold an1protons Hbar* + 4 lasers, radial cooling Ps + Rydberg excita1on Ps* An1H forma1on Hbar* an1protons An1protons Cooled with nega1ve species T<<mK •  Use electric field to manipulate Rydberg an
(AEgIS) •  Easier if Hbar is colder •  Beam for free (small boost (few tens mK) d
to recoil • 
• 
• 
Use the beam Transport to a magne1c trap region Alterna1ve high efficiency an1H trapping scheme Trapped An#H cooling
er cooling : 121 nm Ly-­‐alpha not a commercial laser developed by ATRAP ( T. Haensch and J. Walz, Heidelberg) con1nuous by ALPHA pulsed Limit: mK er cooling Hydrogen with pulsed source has been done ja et al.,1993 Phys. Rev. Le0. 70 2257 er cooling+ adiaba1c cooling ( adiaba1c reduc1on magne1c well) : below mK ling of an1H with 7Li laser cooled : to be inves1gated (???????) Sinha P K, Ghosh A S Phys. Rev. A 72 052509 (2005) Summary
The road toward an1H interferometry and precision spectroscopy includes: -­‐  Ultracooling of an1protons by collisions with nega1ve species laser cooled -­‐  Laser cooling of positronium -­‐  Laser cooling of an1H -­‐  Inves1gate dynamics of collisions between low energy an1H and cold atoms (???) entz viola1on can be Explicit: the Universe just look like this… Inconsistent with Riemann geometry Spontaneous breaking of symmetry A vector or tensor field get a non zero vacuum expecta1on value (Higgs come from a scalar field, no Lorentz viola1on) Consistent with Riemann geometry stelecky, Russel, Tasson PRL 08 sson PRD 2012