Károly Tőkési

Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI)

H--4001 Debrecen, P.O.Box 51, Hungary

Atomic collisions using slow antiprotons in ASACUSA at CERN

+

v

Theory

J. WangDepartment of Physics, University of Massachusetts Dartmouth, North Dartm outh, MA 02747, USA L. GulyásInstitute of Nuclear Research of the Hungarian Academy of Science (ATOMKI), Debrecen, HungaryS. BorbélyFaculty of Physics, Babes-Bolyai University,str. Kogalniceanu nr. 1, 400084 Cluj-Napoca, RomaniaS. Nagele, J. Feist, J. S. Nagele, J. Feist, Burgdörfer

Institute for Theoretical Physics, Vienna University of Technology, A1040 Vienna Austria, EU

Co-workersExperiment

H. Knudsena, H.-P.E. Kristiansena, H.D. Thomsena, U.I. Uggerhřja, T. Ichiokaa,1, S.P. Mřllerb, C.A. Hunnifordc, R.W. McCulloughc, M. Charltond, N. Kurodae, Y. Nagatae, H.A. Toriie, Y. Yamazakie,f, H. Imaof, H.H. Anderseng

a Department of Physics and Astronomy, University of Aarhus, Ny Munkegade Building 1520, 8000 Aarhus C, Denmarkb Institute for Storage Ring Facilities, University of Aarhus, Denmarkc Department of Physics and Astronomy, Queens University, Belfast, UKd Department of Physics, University of Swansea, UKe Institute of Physics, Komaba, University of Tokyo, Japanf Atomic Physics Laboratory, RIKEN, Saitama, Japang Niels Bohr Institute, University of Copenhagen, Denmark

Outlook• Why? – antimatter factory-> new energy source – test of various theories

Experiment – Theorytime-of-flight CC, CDW, CTMC

• Past Single ionization of He Single and double ionization of Ar

• Present Ionization of H and H2

• Future Differential cross sections – anti-cusp

Summary, Conclusions

Dynamic systems with more than one electron

Antiprotons do not capture electrons (one center problem, essentially)Antiprotons follow a classical path (classical orbital approximation)Very slow antiprotons can still ionize ( ”adiabatic” collisions can be investigated)

Advantages with antiprotons:

- Antiprotons can give benchmark data

Antiproton Radiotherapy – application of antiprotons??

V

p Target

Reaction Channels

0

0.2

0.4

0.6

0.8

1 10 100 1000 10000

CERN (90)MEAOCC-2 Igarashi et al (04)IPM-BGM-RESP-2: Keim et al (03)

Energy [keV]

Cro

ss s

ect

ion

[10

-16 c

m2]

Low en

ergy

antip

roto

n dat

a nee

ded

Single ionization of helium by antiproton impact

Ionization of noble gas atoms in slow antiproton collisions

Differential cross sections

Past

“Ionization of Helium and Argon by Very Slow Antiproton Impact”Knudsen et al Phys. Rev. Letters 101 (2008)

“On the double ionization of helium by very slow antiproton impact”Knudsen et al NIMB 267 244 (2009)

Experimental setup

RFQD

武蔵

AIA

extraction line

AIA

TOF SPECTRA

Ionization of helium atoms in slow antiproton collisions

Single Ionization of helium atoms in slow antiproton collisions

THEORY in the year 2009

0

0.2

0.4

0.6

0.8

1 10 100 1000 10000

CERN (08) this workCERN (94) [2]CERN (90) [1]CP frozen core McGowern et al (09)TDCC Foster et al (08) AOCC: Sahoo et al (05) MEAOCC-2 Igarashi et al (04) IPM-BGM-RESP-2: Keim et al (03) LTDSE: Schultz and Krstic (03) TDDFT/OEP-SIC: Tong et al (02) IPM-BGM-RESP-1: Kirchner et al (02) MEAOCC-1: Lee et al (00) MEHC: Bent et al (98) MFIM, 7 cuts: Reading et al (97) IEV: Wehrman et al (96) IPM: wehrman et al (96)

Energy [keV]

Cro

ss s

ectio

n [1

0-16 c

m2 ]

Single ionization of Helium by antiproton impact

Double Ionization of helium atoms in slow antiproton collisions

Double Ionization of helium atoms in slow antiproton collisions

0

0.015

0.030

0.045

1 10 100 1000

CERN (08)TDCC Foster et al (08)BGM-RESP-2: Keim et al (03)BGM-RESP-1: Kirchner et al (01)MEHC : Bent, Krstic and Schultz (98)MFIM no cut: Reading et al (97)MFIM 15 cut: Reading et al (97)CERN (08) upper limit 2CERN (94) two datapoints left outCERN (90)

Energy [keV]

Cro

ss S

ectio

n [A

2 ]

Double Ionization of He by Antiproton Impact

Double Ionization of helium atoms in slow antiproton collisions

1

10

100

1 10 100 1000 10000

CERN (08) this workCERN (08) this work upper limit 2CERN (94) the two datapointsCERN (94) two datapoints left outCERN (89)Puckett and Martin (70) incl captureShah et al (89) incl captureShah et al (89) excl captureShah and Gilbody (85) incl captureShah and Gilbody (85) excl captureKnudsen et al (84)Andersen et al (87)

E [keV]

R =

+

+/

+ [1

0-3]

Helium target

Single ionization of argon atoms in slow antiproton collisions

Double ionization of argon atoms in slow antiproton collisions

Ionization of argon atoms in slow antiproton collisions

Theory:IPM-BGM-RESP

0.1

0.2

0.5

1

2

5

1 10 100 1000

CERN (08)CERN (97)Kirchner et al (02)

Ar++

Ar+

E [keV]

Cro

ss s

ectio

n [1

0-16 c

m2 ]

Ionization of argon atoms in slow antiproton collisions

Theory:IPM-BGM-RESP

10

100

1000

1 10 100 1000 10000

Kirchner et al (02)CERN (08)CERN (97)CERN (89)CERN (87)

Energy [keV]

R =

+

+/

+ [1

0-3]

Argon target

Present

Ionization of H and H2

H+ PRL 74 (1995) 4627

pbar

σH2=2σH?

Future/Theory

Energia (eV)5 10 15 20 25

DD

CS

(cm

2 /sr/

eV)

0

1

2

3

4

5

6X10-17

+

vThe special case of target ionization

25 keV H+ + H(1s)

Total cross sections

Energy (keV)

0 25 50 75 100 125 150

(c

m2 )

2e-17

4e-17

6e-17

8e-17

CTMC

CDW-EIS

Experiment [Hvelplund et al, JPB, 27 (1994) 925.]CDW-EIS [Fainstein et al, PRA 36 (1987) 3639]FIM [Reading et al, 30 (1997) L189]CC [Lee et al, PRA 61 (2000) 062713]TDDFT [Tong et al, PRA 66 (2002) 032709]

Angular differential electron emission cross sections

Ejection Angle (deg.)

0 20 40 60 80 100 120 140 160 180

d/d

(

cm2 /s

r)

1e-19

1e-18

1e-17

1e-16

Ejection angle (deg.)

0 20 40 60 80 100 120 140 160 180d

/d

(cm

2 /sr)

1e-19

1e-18

1e-17

1e-16

50 keV pbar + He 100 keV pbar + HeFirst Born

CDW-EIS- pbar

CTMC- pbar

CDW-EIS- proton

CTMC- proton

Eje

ctio

n A

ngl

e (d

eg.)

20

40

60

80

100

120

140

160

Electron Energy (eV)

20 40 60 80 100 120

Eje

ctio

n A

ngl

e (d

eg.)

20

40

60

80

100

120

140

160

1e-23 1e-22 1e-21 1e-20 1e-19 1e-18 1e-17

20 40 60 80 100 120

(a)

(c)

(b)

(d)

Double differential electron emission cross sectionsE=50 keV

CDW-EIS CTMC

Antiproton

proton

Eje

ctio

n A

ngl

e (d

eg.)

20

40

60

80

100

120

140

160

Electron Energy (eV)

20 40 60 80 100 120 140 160 180 200

Eje

ctio

n A

ngl

e (d

eg.)

20

40

60

80

100

120

140

160

1e-24 1e-23 1e-22 1e-21 1e-20 1e-19 1e-18 1e-17

20 40 60 80 100 120 140 160 180 200

(a)

(c)

(b)

(d)

Double differential electron emission cross sections100 keV

CDW-EIS CTMC

Antiproton

proton

Energy (eV)

0 50 100 150 200

DD

CS

(cm

2 /sr/

eV)

1e-20

1e-19

1e-18

1e-17

1e-16

CDW antiprotonCTMC antiprotonCDW protonCTMC proton

Energy (eV)

0 50 100 150 200

DD

CS

(cm

2 /sr/

eV)

1e-21

1e-20

1e-19

1e-18

1e-17 CDW antiprotonCTMC antiprotonCDW protonCTMC proton

Energy distributions at 0 degree

50 keV pbar + He 100 keV pbar + He

Future/Experiment

PBAR RECYCLER

PBAR COLLIMATION

ELISA

Electrostatic storage ringAarhus University

From protons to biomolecules

Highest storage energy 22 keVAverage pressure <10-11 mBar Circumference 7.6 m Storage time tens of s up to minutes

Is it necessary to detect the antiprotons?

It should be possible to get some information about thetriple differential cross section by detecting the emitted electronand the emitted ion.

Also, remember that the pbar, deflected after ionization can bedetected by their emitted pions

recoil ion

electron

Pbar beam focusing

Capillary with conical shape

• we have obtained experimental benchmark data for the development of advanced models and calculations of atomic collisions in general and for ionization

• we found upper limits to the low energy double ionization cross section and to the ratio between double and single ionization cross sections.

TO BE CONTINUED ……..

Conclusions

Thank you!