Institute of Nuclear Research of the Hungarian Institute of Nuclear Research of the Hungarian Academy of ScienceAcademy of Sciencess (ATOMKI), Hungary (ATOMKI), Hungary

Charged particle guiding through insulator capillaries – from discovery to application

Károly TőkésiKároly Tőkési

Collaborators

Réka BereczkyRéka Bereczky István Rajta István Rajta Gyula Nagy Gyula Nagy

Institute of Nuclear Research of the Hungarian Academy of Sciences

(ATOMKI), Debrecen, Hungary

gold coating

Mylar foil

Ne7+

Neq+

observationangle

tilt angle

Mylar – Nanocapillaries, Stolterfoht et al., PRL 2002

Transmission of HCI through insulating nanocapillaries

• trajectory simulation for projectiles• charge up of insulating surface• deflection of projectiles• random walk simulation for charge transport

Scenario / simulation steps:

Ion guiding

Zq+

inout

bulkj

surfj

Schiessl et al., PRA 72, 062902 (2005); PRL 102, 163201 (2009).

Capillary charging

History

New type of the particle-transport with various samples:

- Nanocapillary arraysMany uncertainties both from experimental and theoretical points of view:

• It is not possible to ensure a perfect parallelism of the nanocapillaries in the foil.• The collective effect of all the neighboring tubes has to be taken into account. • Charge deposition using highly charged ions.

- Single microcapillary − technical applications

It is technically not possible to perform measurements with a single nanotube.

Previous experiments: - slow, highly charged ions (Ne7+, Ar9+)- slow and fast electrons- positron

USING - single straight microcapillary

- single charged and fast ion

- focused microbeam

TARGET - visualization - charge state separation

- measure the energy spectra of the transmitted particles during transmission

Motivation and the aim of the recent studies

Sample

Material: Teflon (Polytetrafluoroethylene)

Parameters: Diameter: 800 μm, Length: 44,15 mm, Aspect ratio: ~ 55

The capillary tilt angle relative to the beam axis is 1o (tilted in horizontal direction).The capillary tilt angle relative to the beam axis is 1o (tilted in horizontal direction).

The position

Sample positioning

With a 5-axis goniometer using

optical microscope and Rutherford Backscattering (RBS) mapping:

With a 5-axis goniometer using

optical microscope and Rutherford Backscattering (RBS) mapping:

Experimental setup

• The beam: 1 MeV proton microbeam

• Spot size: 1 μm

• Beam divergence: 0.01o in the vertical and 0.3o in the horizontal direction

• Intensity: by a Faraday cup, placed behind the sample

• Energy spectra: by a solid state particle detector with about 100-1000 protons/s intensity

Results

Tilt angle: 0°

Tilt angle: 1°

MOVIE

Time evolution

B.S. Dassanayake, R.J. Bereczky, S. Das, A. Ayyad, K. Tőkési and J.A. Tanis, Phys. Rev. A 83 (2011) 012707.

500 eV electron transmissionthrough single straight glass microcapillaryTilt angle 2º

Applicatons

Living cell irradiation

ion

kapilláris sejtmag

Sejttartó tálka

kapilláris

sejt

sejtszerv

hagyományosnagyenergiájúionnyaláb

besugárzott terület

Before irradiation 21 hours later

Kap

illár

is

a) b)

Conclusions

• We observed guiding effect for a macroscopic size teflon capillary with high energy proton microbeam.

• Gradual increase from about 20% to over 90%, where the stable transmission is reached.

• 3 different stages in the energy distribution:

I.Only inelastically scattered contribution with lower than 1 MeV energy

II.The elastic contribution becomes more and more significant

III.Only the 1 MeV peak due to the guiding effect

Application – Proton therapy - cell irradiation TO B

E CONTIN

UED

Thank Thank you!you!