EXPERIMENTAL ACTIVITY IN THE ENEA-FRASCATI IRRADIATION FACILITY WITH 3-7 MEV PROTONS

M. Vadrucci, A. Ampollini, F. Bonfigli, M. Carpanese, F.Marracino, R. M. Montereali, P. Nenzi, L. Picardi,

M. Piccinini, C. Ronsivalle, V. Surrenti, M. A. Vincenti (ENEA Frascati, Roma)

M. Balduzzi, C. Marino, C. Snels (ENEA Casaccia, Roma)

C. De Angelis, G. Esposito, M. A. Tabocchini (ISS, Roma),

F. Ambrosini, M. Balucani, A. Klyshko (Sapienza University of Roma - DIET, Rome)

Porous Silicon

AbstractA variable energy (3-7 MeV) and pulsed current (0.1 – 100 µA) proton beam has been made available for different applications (radiobiology experiments, detectors development, material studies) in an irradiation facility at ENEA-Frascati based on the 7 MeV injector of the proton-therapy linac under realization in the framework of the TOP-IMPLART Project. It is a 425 MHz linear accelerator consisting in a 3 MeV RFQ followed by a DTL up to 7 MeV (PL-7 ACCSYS HITACHI model) followed by an horizontal and a vertical beam transport line. The latter one is particularly suitable for radiobiology in vitro studies allowing to irradiate besides cell monolayers also cell growing in suspension culture. The paper describes the facility and the recent results of the experimental activity.

1. TOP-IMPLART AT ENEA-FRASCATI

3. HIGH FLUENCE PROTON BEAM

HORIZONTAL TRANSPORT LINE

,

2. LOW FLUENCE PROTON BEAM

VERTICAL TRANSPORT LINE

RADIOBIOLOGY EXPERIMENTS

LiF-Detectors development

The TOP-IMPLART layout

3-7 MeV Protons Irradiation Facility

TOP IMPLART PROJECT

Oncological Therapy with Protons – Intensity Modulated Proton Linear Accelerator for

RadioTherapy

- ENEA, ISS, IFO collaboration –

to build a proton-therapy linac to be housed in the largest

oncological hospital in Rome, IFO.

VARIABLE CURRENT 30keV SOURCE

VERTICAL LINE TERMINAL

HORIZONTAL LINE EXTRACTIONS

3 – 7 MeV

RFQ DTL

Spatial dose distribution on Gaf-Chromic EBT3 film

90%uniformity

KAPTON WINDOW 50m THICK

Au SCATTERER 2m THICK

Al COLLIMATOR 2mm DIAMETER

MYLAR 50 m THICK

6m V79

Sample holder for cells MeV keV/m protons/cm2 A s Hz Gy/min

5 7.7105÷10

6 0.16 13 6.25 2

exponential increase of cell death

increasing Dose as expected from the Linear Quadratic

Model of the Surviving Fraction

with Dose for low LET radiation exposures

Transferred pattern after porous silicon removal

Cross section of exposed silicon after porous silicon formation.

The area in the image corresponds to the edge of one masked area.

Porous silicon appears lighter in the image and has a rough texture.

The thickness of the non-porous area is 31µm because of the imaging angle (67°)

Experimental setup used to irradiate silicon sample

PROTONS ENERGY= 1.8 MeV

FLUENCE= 1014 – 1015 protons/cm2

SAMPLE: 1.5 x 1.5cm2 p-type silicon doped with Boron (100) - 1-10 Ohm*cm

PATTERN: Molybdenum mask to transfer patterns on silicon

ANALYSIS: FESEM (Field Emission Scanning Electron Microscope)

Porous Silicon for Micro-Electro-Mechanical-Systems

Silicon Bulk Micromachining

- Integrated visible photoluminescence signal as a function of the 3 and 7 MeV proton fluence in irradiated LiF films

- PL image of the proton beam transversal section stored by CCs

PROTONS ENERGY= 3 and 7 MeV

FLUENCE= 1011 – 1015 protons/cm2

SAMPLE: (10 x 10 x 1) mm3 LiF crystals and 1 mm thick LiF films grown by thermal evaporation on glass substrates

ANALYSIS: PhotoLuminescence (PL) Spectrometer and Fluorescence Optical Microscopy (with a cooled s-CMOS camera to record the transversal proton beam intensity profile by acquiring the PL image of irradiated LiF)

Imaging Detectors based on the optical reading of the photoluminescence (PL) of radiation-induced visible-emitting colour

centres (CCs).

The average F, F2 and F+3 defect vs fluency

PL spectra of samples irradiated with a fluence of 5.6 1013 protons/cm2