1. Research Programme at the LEPTA Facility
29th Meeting of the PAC for Nuclear Physics
January 22–23, 2009
Research Programme at the LEPTA Facility
I.Meshkov for LEPTA collaboration
Dzhelepov Laboratory of Nuclear Problems

2. Low Energy Particle Toroidal Accumulator
LEPTA Collaboration
I.Meshkov Research Programme at the LEPTA Facility PAC NP
Low Energy Particle Toroidal Accumulator
LEPTA Ps
DLNP JINR
Yu.K.Akimov, E.V.Ahmanova, V.F.Bykovsky, A.G.Kobets,
V..Lokhmatov, V.N.Malakhov, V.N.Pavlov, R.V.Pivin,
A.Yu.Rudakov, L.V.Soboleva, T.A.Stepanova, S.L.Yakovenko
BLTP JINR E.A.Kuraev
Lomonosov Pomorsky State University (Arkhangelsk) M.K.Eseev
INR RAS (Troitsk) A.B.Kurepin, V.I.Razin, A. I.Reshetin
Lebedev IP RAS (Moscow) N.N.Kolachevsky
ITEP (Moscow) V.I.Grafutin, O.V.Ilyushkina, E.P.Prokopev
INP BSU (Minsk) V.G.Baryshevsky, A.Ya.Silenko
IKP FZJ (Juelich) J. Dietrich, D. Grzonka, V. Kamerdjiev, W. Oelert
University of Wales Swansea/CERN M. Charlton, L.V. Jorgensen
iThemba Labs ( SAR) L.Conradie, C.Naido
FLAIR Collaboration (FAIR) E.Widmann, M.Grieser, K.Welsh, A.Wolf

3. LEPTA Ps Contents 1. LEPTA facility: the scheme and design parameters
Research Programme
at the LEPTA Facility
I.Meshkov for LEPTA collaboration
Dzhelepov Laboratory of Nuclear Problems
Joint Institute for Nuclear Research
Dubna 2009
29th Meeting of the PAC
for Nuclear Physics
January 22–23, 2009
Contents
1. LEPTA facility: the scheme and design parameters
2. The main goals of the LEPTA project
3. Peculiarities of the experiments conditions at the LEPTA
4. Electron-positron recombination in-flight
5. Positronium spectroscopy and QED tests
6. ParaPositronium generation and studies
7. Experiments with orthoPositronium in-flight
8. Some concepts of Ps-detectors
9. Condensed matter studies with positron annihilation
spectroscopy at LEPTA positron injector
10. Antihydrogen and Positronium in the FLAIR project
11. LEPTA facility status and the nearest plans
Conclusion
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

4. 1. LEPTA facility: the scheme and design parameters
kicker
septum
cooling section Ps
detector
10E4 o-Ps per sec
e-gun
positron trap
10E6100sec=10E8 e+
Helical quadrupole
22Na
10E6 e+
per sec
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

5. LEPTA Ps Positron injector 4 5 1 2 9 10 3 8 11 67 1 2 9 10 3 8 11 6
LEPTA entrance
Positron injector
1-positron source 22Na, 2-radioactive protection shield, 3-vacuum valve, 4-vacuum chamber for pumping out and diagnostic tools, 5-positron trap, 6 – vacuum isolator, 7 – positron vacuum channel, 8 – vacuum “shutter” (fast valve), 9 - ion pump, 10-turbopump, 11 –LHe vessel
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
1. LEPTA facility: the scheme and design parameters

6. 1. LEPTA facility: the scheme and design parameters
LEPTA ring
Injector
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

7. LEPTA Ps Design Parameters of The LEPTA Facility Circumference , m
1. LEPTA facility: the scheme and design parameters
Design Parameters of The LEPTA Facility
Circumference , m
17.2
Positron energy, keV
4.0  10.0
Revolution time, ns
500  300
Longitudinal magnetic field, G
400
Average radius of the toroidal magnets, m
1.45
Helical quadrupole gradient, G/cm
10.0
Positron beam radius, cm
0.5
Number of positrons in the ring
1E8
Residual gas pressure, nTorr
 0.1
orthoPositronium beam parameters
Intensity, atom/s
110
oPs atom velocity, m/s
(3.8 6)E7 (β  0.12  0.2)
Angular spread, mrad 1
Velocity spread
1104
Beam diameter at the exit of the ring, cm
1.1
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

8. 2. The main goals of the LEPTA projectPs
I.Meshkov Research Programme at the LEPTA Facility PAC NP
2. The main goals of the LEPTA project
Particle dynamics in LEPTA
Electron cooling of positrons
Positronium generation in-flight
Experiments on Positronium physics
Feasibility studies of slow antihydrogen
generation in-flight
Applied research (Positron
Annihilation Spectroscopy)

9. 3. Peculiarities of the experiment conditions at the LEPTA
The peculiarities and advantages of o-Ps generation at LEPTA:
1) Generation in-flight  pure vacuum conditions, no influence
of a surrounding matter.
2) The o-Ps flux has a small angular and velocity spread.
3) One can scan the o-Ps velocity with a high precision by variation of the electron energy, because positrons are “carried away” by electrons (getting the electron velocity): e e+
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

10. LEPTA Ps 4. Electron-positron recombination in-flight
I.Meshkov Research Programme at the LEPTA Facility PAC NP
4. Electron-positron recombination in-flight
The application of electron cooling in LEPTA allows us to measure, with a high precision, the dependence of recombination coefficient (“recombination cross section”) on temperature of the recombining particles:
The electron temperature variation can be produced
by modulation of electron energy with a frequency
f >> 1/(_cool) ~ 10 MHz .
It will be the very first experiment on Positronium physics at LEPTA and is of interest of quantum mechanics.
Peculiarities: both electron and positron are “magnetized”, electron density distribution is non-isotropic - so called “flattened distribution”.
(See details in The Hard Copy of the report).
Recombination of positrons with cooling electrons is an unavoidable process at electron cooling of positrons.

11. LEPTA Ps 5. Positronium Spectroscopy and QED tests
I.Meshkov Research Programme at the LEPTA Facility PAC NP
5. Positronium Spectroscopy and QED tests
Why Ps spectroscopy is interesting?
The importance of precise measurement of Ps states characteristics relates to fundamental problems of QED. It will suffice to mention the relativistic problem of two-body bound system (the Bethe-Salpeter equation approach, etc.), which still needs in precise experimental tests for its further development. Positronium, as a system of two electromagnetically bound particles, is a very fertile ground for such an application.
See details in S.Karshenboim, Precision Study
of Positronium: Testing Bound State QED Theory,
Intern. Journal of Mod. Phys. A19 (2004) 3879
Two possible experiments – measurement of
5.1) Hyperfine structure of Ps ground state
5.2) Spectroscopy of excited states, Lamb shift

12. “Triple fitting” (_RF, v_oPs, B)
5. Positronium Spectroscopy and QED tests
5.1) Hyperfine structure of Ps ground state
Parameter
Theory
Experiment
Value
Precision
Ground state energy , eV
6.79 -
Hyperfine splitting energy
13S1 - 11S0 , eV
MHz
8.411·10E-4
(16)
·10E-4
(0.74)
 3.6·10E-6
“Triple fitting” (_RF, v_oPs, B)
The result: Hyperfine splitting of Ps ground state can be measured with accuracy ( / )_HFS < 1E-6 or better (instead 3.6E-6).
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

13. LEPTA Ps 5.2) Spectroscopy of excited states, Lamb shift
I.Meshkov Research Programme at the LEPTA Facility PAC NP
5. Positronium Spectroscopy and QED tests
5.2) Spectroscopy of excited states, Lamb shift
Transition frequency, MHz
23 S S0
23 S P1
23 S P2
23 S P1
23 S P0
Transition -
(0.06)
 8E-4
11180(5) (4)
(0.13)
 4.7E-4
(2.7)(0.9)
(0.13)
1.5E-4
(0.67)(1.54)
(0.13)
 2.7E-4
(1.20)(4.00)
(0.13)
Precision
Value
Experiment
Theory
Rather low precision
of experimental data
Experiment:
One can improve the precision by several
orders of magnitude.
Main limitation – statistics:
a poor occupancy of excited levels

14. LEPTA Ps 5.3) Two-photon 13S1 – 23S1 transition  2.6E-9
I.Meshkov Research Programme at the LEPTA Facility PAC NP
5. Positronium Spectroscopy and QED tests
5.3) Two-photon 13S1 – 23S1 transition
 2.6E-9
5.1
(32)
(1.0)
13 S S1 *)
transition energy, eV frequency, PHz -
6.79
Ground state energy , eV
Precision
Value
Experiment
Theory
Parameter
Laser Doppler-free spectroscopy
of two-photon 13S1 – 23S1 transition measurement
M.S.Fee, A.P.Mills et al.,1993
Very important, but… very hard experiment:
One can hope to improve the precision
by several times.
Main limitation – statistics:
a small number of two photon transitions.

15. Two experiment schemes
2-photon
transition
Photoionisation,
Nd:YAG laser,
2nd harmonics
5. Positronium Spectroscopy and QED tests
5.3) Two-photon 13S1 – 23S1 transition
Two experiment schemes
M.S.Fee, A.P.Mills e al.,1993
Different scheme
13S1, m = 0, 1
13S0
23P0,1,2
Spontaneous decay
(L) = 243 nm, (L) = 3.2 ns
Interference of 13S1, m = 0 and 11S0 states in B-field
with fast decay of p-Ps state
RF induced
transition: 8.6, 13.0, 18,5 GHz
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
See details in The Hard Copy of the report

16. LEPTA Ps 6. ParaPositronium generation and studies
6.1. QED test in measurement of p-Ps life time
The experiment principle:
interference of
11S0 and 13S1 (m=0) states
in magnetic field
Experiment PALM:
para-Positronium Life Time Measurement
ΔE /E1S
1.5
1.0
-1.0
-1.5
B, [ T ]
m = 0
m = ±1
13S1
11S1
E1S
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

17. 6.1. QED test in measurement of p-Ps life time: experiment PALM
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
6. ParaPositronium generation and studies
6.1. QED test in measurement of p-Ps life time: experiment PALM 
o-Ps
o-Ps/p-Ps
N1(B) – number of counts during time
interval T1 when solenoid field B is ON,
N2 – the count number during T2 when B = 0.
The function
to be measured:
NbTi
Target
130 mm
PMTube
BGO-crystal
 1 m Fe
SC solenoid
150 mm
Pick-off annihilation

18. 6. ParaPositronium generation and studies
6.1. QED test in measurement of p-Ps life time: experiment PALM
Theory
Experiment
Precision
p-Ps lifetime, ps
125.16(08)
(27)
2E-4
The only experiment on para-Ps life time measurement is known ! (A.H.Al_Ramadhan, D.W.Gidley, PRL 72 (1994) 1632)
To obtain the necessary statistic precision p / p = 1·10-4
one has to register in PALM experiment
Nexp  41010 events number.
The full duration of the experiment will be of ~ 9 months.
The PALM project was presented to PAC NP at 21st (Nov.2004) and 22nd (April 2005) meetings and has been approved (see details in The Hard Copy).
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

19. LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
6. ParaPositronium generation and studies
L.B. Okun’,
“C, P, T are broken. Why not CPT?”
In Proc. Of 14th Rencontres de Blois
"Matter-Antimatter, June ,
edited by L. Iconomidou-Fayard and
J. Tran Than Van (The Gioi Publishers) k -k
 = +1
 = -1
p-Ps
The asymmetry in number of the left- and right- circularly polarized photons would be a signal that CPT is broken.
6.2. Test of CPT theorem in search for circularly polarized photons in p-Ps =>  
The p-Ps flux can be ~ 3000 с-1 at LEPTA design parameters. That allows us to reach, at k ~ 3·10-3, the level of
 < 1·10-8
at the experiment duration ~ 1 year (see details in The Hard Copy).

20. LEPTA Ps 6.3. Rare and forbidden decay channels of p-Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
6. ParaPositronium generation and studies
CL 90%
< 2.8E-6 -
p-Ps  3 , Г(3)/ Г(2)
Relative probability of forbidden decay
Branching ratios of rare decay rates
Precision
Value
Experiment
Theory
Parameter
< 2.7E-7
< 10-27
p-Ps  5 , Г(5)/ Г(2),
1.14(39)E-6
1.4388(21)E-6
p-Ps  4, Г(4)/Г(2)
2·10-4
(27)
125.16(08)
Life time, ps
6.3. Rare and forbidden decay channels of p-Ps

21. LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
6. ParaPositronium generation and studies
Application of o-Ps flux of the LEPTA design intensity of ~ 10E4/sec and generation of p-Ps by a target bombardment one can decrease the branching ratio level for rare and forbidden decay channels
up to 1E-8 – 1E-9.
The main task is design and construction
of a multipurpose detector
(see section 8 in The Hard Copy).
6.3. Rare and forbidden decay channels of p-Ps

22. LEPTA Ps 7. Experiments with orthoPositronium in-flight
I.Meshkov Research Programme at the LEPTA Facility PAC NP
7. Experiments with orthoPositronium in-flight
7.1. Test of CPT theorem in direct comparison
of e+e- electric charges:
Project Electron-POsitron Charge Comparison
The EPOCC experiment concept:
o-Ps “non-deflection” in transverse magnetic field.
o-Ps 
Co-ordinate detector
CsI B
p-Ps

23. LEPTA Ps e/e < 410-10 The method resolution:
I.Meshkov Research Programme at the LEPTA Facility PAC NP
7. Experiments with orthoPositronium in-flight
<4E-8
Experiment
< 1(2)4E18
Charge inequality e/e
Precision
Theory
Parameter
If Ee= 10 keV, x~0.1 mm, BLm, one can obtain
e/e < 410-10
The method resolution:
L is the o-Ps trajectory length in the field,
p is electron (positron) momentum.
7.1. Test of CPT theorem in direct comparison
of e+e- electric charges (project EPOCC)
(See the resolution of 17th session of the PAC for Nuclear Physics, November 2002 in The Hard Copy and the comments there)

24. LEPTA Ps 7. Experiments with orthoPositronium in-flight
I.Meshkov Research Programme at the LEPTA Facility PAC NP
7. Experiments with orthoPositronium in-flight
7.2. Rare and forbidden decay channels of o-Ps
CL 90%
< 3.5E-6
< 1E-27
o-Ps  2 , Г(2)/ Г(3 )
< 2.8E-4
(“invisible decay”)
6.2E-18
o-Ps  (~)e , Г(~)e / Г(3)
Branching ratios of weak decay rates
< 2.6E-6
o-Ps  4 , Г(4)/ Г(3)
2E-4
2.2 ( stat. 0.5 syst.)E-6
1E-6
o-Ps  5 , Г(5)/ Г(3)
Branching ratio of forbidden decay rates
Branching ratio of rare decay rate
Precision
Value
Experiment
Theory
Parameter
9.5E-21
o-Ps  (~), , Г(~),/ Г(3)
At o-Ps flux of ~ 10E4/sec one can improve the precision
of rare decay branching ratio and decrease the upper level
values of the forbidden decays up to 1E-8 – 1E-9.

25. Branching ratios in decay o-Ps  A, 7.3. Search for the Light Axion
7. Experiments with orthoPositronium in-flight
Branching ratios in decay o-Ps  A,
7.3. Search for the Light Axion
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
References
(see next slide)
What
do we
know
today?
Experiment
“Old” theory
“New” theory: m_Axion  0.1 eV => a candidate for Dark Matter constituent

26. 7.3. Search for the Light Axion
7. Experiments with orthoPositronium in-flight
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
References
[1] S. Orito et al., Phys.Rev.Lett. 63, 597 (1989).
[2] U. Amaldi et al., PL, 153B, 444 (1985).
[3] G. Carboni and W. Dahme, PL, 123B, 349 (1983).
[4] S. Asai et al., PL, 323B, 90 (1994).
[5] M. Tsuchiaki et al., PL, 236B, 81 (1990).
[6] V. Metag et al., Nucl.Phys. 409A, 331 (1983).
[7] W. Bernreuther and O.Nachtmann, Z.Phys., 11C, 235 (1981).
[8] M.V. Akopyan et al., PL, 272B, 443 (1991).
*Region Br<2.8∙10-5 m<30 keV
[9] S. Asai, S. Orito, et al., Phys. Rev. Lett. 66, (1991)
[10] T. Maeno et. al., PL, 351B, (1995)
[11] S. N. Gninenko et. al., PL, 237 B, (1990)
*Region Br < 3.8E-4 m < 30 keV
Theory:
Rev. of Part.
Physics (2008) 479
7.3. Search for the Light Axion

27. LEPTA Ps Why we are so interested of the Axion (A0)?
7. Experiments with orthoPositronium in-flight
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
7.3. Search for the Light Axion
“The Axion (A0) - a light, neutral, short-lived and weakly interacting boson, is among the two best known and most studied cold dark matter candidates… The Axion is predicted by extensions of the Standard Model which resolve the strong CP problem. Its mass must be approximately 10E-5 eV…”
[Eur. Phys. J. C 3 (1998) 125]
Why we are so interested of the Axion (A0)?

28. LEPTA Ps Statistics and the experiment duration:
7. Experiments with orthoPositronium in-flight
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
7.3. Search for the Light Axion
Statistics and the experiment duration:
At the branching of 10E-10 one needs to have ~
~ 10E10 o-Ps integral flux.
That requires ~ 10E6 sec  280 h facility run
at design o-Ps intensity and 100% detector efficiency.
(See details in The Hard Copy, section 8).
One has to look for single photons in o-Ps decay!
Unfortunately, peculiarity of 500 keV -quanta interaction with
matter does not allow us to construct an efficient tracking!
Only criterion we have is photon energy measurement.
(See details in The Hard Copy, section 8)

29. the hypothesis of “The Mirror Universe"
7. Experiments with orthoPositronium in-flight
7.4. o-Ps life time and
the hypothesis of “The Mirror Universe"
This is another fascinating task related to Ps physics. Formulated in the 60th by I.Kobzarev, L.Okun’ and I.Pomeranchuck the idea of The Mirror Universe was developed later by S.Glashow and others.
One associates nowadays The Mirror Universe
with
The Dark Matter and “The Brane World”
[See L. B. Okun', Uspekhi Phys. Nauk, 177 (2007) 397].
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

30. LEPTA Ps i.e. o-Ps atoms “escaping” into the Mirror World!
7. Experiments with orthoPositronium in-flight
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
7.4. o-Ps life time and the hypothesis of “The Mirror Universe"
The Basic Idea:
I Kobzarev, L.Okun, I.Pomeranchuk [Yad. Fiz., 3 (1966]
T.D.Lee and C.N.Yang (1960): L- particles (“usual”)
R-particles (“mirror”)
L- and R- particles can interact only by exchange with photons or gravitons.
The idea of a test:
S.Glashow [Phys. Letters 167B (1986) 35], Positronium as a test system: an existense of “the disappearing o-Ps”,
i.e. o-Ps atoms “escaping” into the Mirror World!

31. LEPTA Ps And the idea of a test relates to
7. Experiments with orthoPositronium in-flight
7.4. o-Ps life time and the hypothesis of “The Mirror Universe"
And the idea of a test relates to
a precise measurement of o-Ps life time !
Present status:
Precision
Value
Experiment
Theory
Parameter
2.5E-4
1.0E-4
(0.02)(0.016) R.S.Vallery et. al., 2003
(14) S.Asai et al., 2008
Life time, ns
“The puzzle” of o-Ps life time is over!
However, the task of the precise measurement remains…
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

32. 7. Experiments with orthoPositronium in-flight
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
7.4. o-Ps life time and the hypothesis of “The Mirror Universe"
S, [m]
1E-6
-1E-6
-2E-6
- 3E-6
(s)
The Task for the experiment is to measure the distribution of o-Ps intensity along the travel channel (s co-ordinate):
N(s)/N(0) = exp{-s/)}·cos2(s/v)  exp{-s/v} - (s),
(s) = exp{-s/v}∙ (s/v)2 ,
 is Lorentz-factor of o-Ps.
An example:
v = 6·107 m/s (10 keV/u) ,
 = 3·10 - 8
The measurement
of (L) ~ 2E-6
requires
N(si) ~ 2.5E11
i.e. ~ 1 year
data acquisition
at oPs flux ~ 1E4 s-1.

33. LEPTA Ps 8. Some concepts of Ps-detectors
I.Meshkov Research Programme at the LEPTA Facility PAC NP
8. Some concepts of Ps-detectors
8.1. Positron pick-off detector 
o-Ps
130 mm
PMTube
BGO-crystal
Pick-off annihilation
YAP crystall
4π detector
“BGO Ball”
Detector consists of 30 BGO-counters situated at a spherical surface and the target placed in the center of the sphere. As a target in the “Pick-off Detector” is used scintillating YAP crystal (Ce: YAlO3).
(See details in The Hard Copy, section 8).

34. LEPTA Ps 8. Some concepts of Ps-detectors
I.Meshkov Research Programme at the LEPTA Facility PAC NP
8. Some concepts of Ps-detectors
8.1. Positron pick-off detector
The pick-off detector will be applied
in the following experiments:
- Electron-positron recombination in-flight (section 4),
- Ps spectroscopy (sections 5.1, 5.2, 5.3(?),
- Experiment PALM (section 6.1),
- Experiment EPOCC (section 7.1),
- Precise measurement of o-Ps life time and search
for The Mirror Universe (section 7.4).
(See details in The Hard Copy, section 8.)

35. LEPTA Ps 8. Some concepts of Ps-detectors
I.Meshkov Research Programme at the LEPTA Facility PAC NP
8. Some concepts of Ps-detectors
8.2. Gamma-quanta detector for o-Ps decay in-flight
A.B.Kurepin and team (INR RAS)
Such a detector will be based on NaI (CsI?) crystals and Micropixel Avalanche Photodetectors (MAP). Efficiency of registration is close to 100%.
MAP
o-Ps
Plastic scintillator cut
in cylindrical sectors
The diodes analyze TOF and amplitude of a signal.
[Absorption length of 500 keV -quanta in NaI  2.1 cm ]
(See details in The Hard Copy, section 8).
8 – 10 m

36. LEPTA Ps 8. Some concepts of Ps-detectors
I.Meshkov Research Programme at the LEPTA Facility PAC NP
8. Some concepts of Ps-detectors
8.2. Gamma-quanta detector for o-Ps decay in-flight
(See details in The Hard Copy, section 8).
The gamma-quanta detector will be applied
in the following experiments:
- Rare and forbidden decays of p-Ps (section 6.3)
- Rare and forbidden decays of o-Ps (section 7.2),
- Search for The Light Axion (section 7.3).
(See details in The Hard Copy, section 8.)

37. LEPTA Ps 9. Condensed matter studies
I.Meshkov Research Programme at the LEPTA Facility PAC NP
9. Condensed matter studies
with positron annihilation spectroscopy
at LEPTA positron injector
Positron injector and transfer channel
e+ injector
Acceleration gap
+10 kV
Research stand
0 ÷ - 70 kV
The project is applied for RFBR grant 2009 in collaboration
with ITEP group.

38. 10. Antihydrogen and Positronium Positron Cooler Storage Ring
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
10. Antihydrogen and Positronium
in The FLAIR Project
Positron Cooler Storage Ring
at FLAIR
“Budker’s scheme”
(G.Budker, A.Skrinsky,1978) p _
H, p
o-Ps

39. LEPTA Ps 11. LEPTA Facility Status and The Nearest Plans
11.1. LEPTA ring development: test with circulating electron beam
2005 year
400G
510G
Life Time vs Electron Energy
Life Time, ms
Electron energy, keV
470G
P  5E-8 Torr
June 2008
400 G
510 G
Life Time vs Electron Energy
Life Time, ms
Electron energy, keV
October 2008
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

40. LEPTA Ps 11.2. Cryogenic Positron Source
moderation
in frozen Neon
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
T ~ 5 K
22Na Ne e+
11. LEPTA Facility Status and The Nearest Plans
11.2. Cryogenic Positron Source
Test bench for the e+ source
Positron source
E E5
Positron Energy Spectrum of 22Na Isotope and the moderation effect
Positron energy spectrum of 22Na
Moderated positrons

41. LEPTA Ps 11.2. Cryogenic Positron Source
I.Meshkov Research Programme at the LEPTA Facility PAC NP
11. LEPTA Facility Status and The Nearest Plans
11.2. Cryogenic Positron Source
The positron spectrum at the e+ flux of 1.75*103 positrons per sec
of the average energy of 1.2 eV at the width of 1 eV was obtained
in experiments with test Na-22 radioactive source of low activity
of 0.8 MBq (2005) .
The moderation efficiency was of 1.0 %.
Slow Positron Yield
vs Frozen Neon Thickness
d, mcm
2000
1600
1200
800
400
Ncounts/sec
130мкм
90мкм
50м км
30мкм
Epos, eV
Slow Positron Spectrum
16000
12000
8000
4000
dN/dE

42. LEPTA Ps e+ source of 25 mCi activity
I.Meshkov Research Programme at the LEPTA Facility PAC NP
11. LEPTA Facility Status and The Nearest Plans
11.2. Cryogenic Positron Source
e+ source of 25 mCi activity
Na_22 positron source of activity of 25 mCi for LEPTA facility
has been donated by iThemba LABS (RSA) and transferred to JINR:
it has been received February 27, 2008 and not mounted yet due to
delay with injector elements manufacturing.

43. 11.3. Positron trap (“The Surko trap”)
11. LEPTA Facility Status and The Nearest Plans
11.3. Positron trap (“The Surko trap”)
Area 1
Area 2
Area 3 eU z
10-3
Pressure, Torr N2 е+
10-4
10-6
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP

44. The trap has been tested with electrons of ~ 50 eV energy.
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
11. LEPTA Facility Status and The Nearest Plans
11.3. Positron trap
The trap has been tested with electrons of ~ 50 eV energy.
Stored electron number vs time
Same + transverse correction field is optimized
Same + rotating field is ON and optimized
Pressure distribution and potential are optimized
“The rotating wall “method application:
Optimal “wall” parameters:
Frequency = 650 kHz,
Amplitude = 1 V,
ε = 0.4, life = 80 s

45. 11.4. Injector status summary
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
11. LEPTA Facility Status and The Nearest Plans
11.4. Injector status summary
1.0
0.5
Efficiency of the 22Na spectrum transformation, %
Achieved
Design
Parameter
1E-4
1E8
300
100
1E-9
1000
4  10
310E-8
Vacuum, Torr
80 (e-)
Positron life time in the trap, sec.
500 (e-)
Pulse duration of extracted positrons, ns -
Momentum spread of extracted positrons, p/p
0.8E8 (e-)
Positron number per pulse
< 0.5
Positron beam radius, cm
1500
Magnetic field in the Trap, G
Positron energy, keV

46. 11.4. Injector status summary
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
11. LEPTA Facility Status and The Nearest Plans
11.4. Injector status summary
Injector completion:
e+ transfer channel
manufacturing and
mounting of e+ source.
Transfer channel
e+ injector

47. 11.5. The ring development status
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
11. LEPTA Facility Status and The Nearest Plans
11.5. The ring development status
Test with electrons – in progress,
Trajectory of cooling electrons has been tested,
Electron cooling system – close to completion,
Diagnostics of circulating electron beam – under preparation.
11.6. The nearest plans
The main goals: positron injection into the ring,
electron cooling of positrons
and Positronium generation.
Year 2009

48. Thank you for your attention!
LEPTA Ps
I.Meshkov Research Programme at the LEPTA Facility PAC NP
Conclusion
The proposed research Programme at the LEPTA facility is very attractive for both fundamental and applied experimental studies based on Positronium flux and monochromatic positrons.
The Programme needs an approval by PAC and JINR Directorate and the team at DLNP needs corresponding support.
The interest to the LEPTA project was expressed by many collaborating groups and they will form a research community at LEPTA facility as soon as the facility construction and commissioning is completed.
Thank you for your attention!