Experimental activity on the TOP-IMPLART linear accelerator

Fabrizio Ambrosini Sapienza University of Rome - DIET, Rome

M. Vadrucci, A. Ampollini, G. Bazzano, F. Bonfigli, 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)

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

M. Balucani, R. Cicchetti, A. Klyshko (Sapienza University of Roma - DIET, Roma)

TOP - IMPLART Project

VARIABLE CURRENT 30keV SOURCE

3 – 7 MeV

RFQ DTL

VERTICAL LINE TERMINAL

HORIZONTAL LINE EXTRACTIONS

3cm

7mm

SCDTL-1 PMQ

Outline

• Experimental results on the first SCDTL module (7-11.6 MeV):

• Simple characterization method of small high gradient permanent magnet quadrupoles (PMQs)

• Experimental results with low energy (3-7 MeV) proton beams:

- Radiobiological experiments

- LiF detectors development

- Porous Silicon for micromachining

- RF cold tests

- Proton beam transport: propagation in a short DOFO channel (4PMQs)

- Proton beam transport: propagation in the complete DOFO-like channel

(9PMQs) mounted on the SCDTL (RF off)

- RF hot tests

Experimental results with low energy (3-7 MeV) proton beams

Low proton fluences (106 protons/cm2): VERTICAL BEAM LINE

High fluences (> 1010 protons/cm2): HORIZONTAL BEAM LINE

for the study of in vitro models of cellular mechanisms involved in the carcinogenesis process development

to develop a LiF particle detector and to realize porous silicon for Micro-Electro-Mechanical-Systems (MEMS)Q 1 Q 2 Q 3 Q 4

High fluences

Q 2 Magnet 90°

Low fluences

Q 1

A campaign of radiobiology experiments has started on Chinese Hamster V79 cells for cell killing induction studies within a dose range of 0.5 - 8 Gy at different:- beam energies - dose rates (i.e. varing the charge for pulse) - dose (varying the irradiation time)

Cells with their culture liquid (6μm thickness), in a cylindrical sample holder with a diameter of 13 mm

Mylar sheet (50μm thickness)

Dosimetric control: GafChromic films EBT3 suitably calibrated at LNL Laboratories. The irradiated area has a uniformity of 90%

The dose response curve obtained was in agreement with literature data

Radiobiological experiments

Kapton window 50m thickAu scattere 2m thick

Al collimator 2mm diameter

Beam characteristics during V79 cells irradiation

MeV Prot/cm2 μA μs Hz Gy/min

5 1011 -1015 0.16 13 6.25 2

LiF detectors development

The irradiation of LiF induces the formation of primary and aggregate CCs, which are stable at RT. By a fluorescence optical microscope equipped with a cooled s-CMOS camera, it was possible to record the transversal proton beam intensity profile by acquiring the PL image of irradiated LiF.

Linear behaviour with fluence covering several orders of magnitude of fluence range, irradiating LiF films grown on a glass substrate.

F2 ed F3+ luminescono nel rosso

(670nm) e nel verde (530 nm)

Energy (MeV) Fluence range Sample

3 - 7 1011 - 1015 LiF films (1μm thickness) LiF crystals

Porous Silicon for Micro-Electro-Mechanical-Systems Silicon Bulk Micromachining

Energy (MeV) Fluence (prot/cm2) Sample Pattern Analysis

1.8 1014 – 1015 1.5 x 1.5 cm2 p-type silicon doped with Boron (100) - 1-10 Ohm*cm

Molybdenum mask to transfer patterns on silicon

FESEM (Field Emission Scanning Electron Microscope)

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 (corrisponding to the stopping range of 1.8 MeV) because of the imaging angle (67°).

Experimental setup used to irradiate silicon sample

Transferred pattern after porous silicon removal

RF cold test: the structure has been tuned and completely characterized on RF bench

Smith chart showing the coupling of the π/2 mode Q reflection measurement

Resonant modes measured in reflection from the central tank

The measured modes dispersion curve

Experimental results on the first SCDTL module (7-11.6 MeV)

0 0.2 0.4 0.6 0.8 1

2.96

2.98

3

3.02

3.04

3.06

phi (pi units)

Fre

quen

cy(G

Hz)

SCDTL24aprile

w1(GHz)= 3.01077w2(GHz)= 2.99238k= 0.02872k1= -0.00927k2= 0.00357Stop Band(GHz)= 0.00081

2960 2970 2980 2990 3000 3010 3020 3030 3040 3050

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2MARK Freq=2997.635 MHz Val=-19.073 Fmin=2997.64

Bead pull measurement: squared electric field along the axis on the SCDTL structureTuners for tuning

acceleranting tanksTuners for tuning coupling cavity and flattening the field

Holes for pickups

Proton beam transport: propagation in a short DOFO channel (4PMQs)

Beam spot after 1 PMQ (#1) in position 4

Beam spot after 1 PMQ (#2) in position 4

Beam spot after 4 PMQ (#1,2,3,4)

Fluorescent target

The final beam spot on a fluorescent target (included within a diameter of 4mm)

Proton beam transport: propagation in the complete DOFO-like channel

(9PMQs) mounted on the SCDTL (RF off)

Main settings during the experiment

Extraction voltage, kV 28.2

Einzel voltage, kV 27.8

Q1 Gradient, T/m -9.1

Q2 Gradient, T/m 8.87

Q3 Gradient, T/m -10.15

Q4 Gradient, T/m 12.02

The reduction of the transmission (60% of 200μA in input) respect to the computed value (84% for a 7MeV beam with a nominal energy spread included in ±100 keV) is due:

• mainly to the presence of a low energy satellite in the input beam.

• to residual misalignements

Arc current

DTL field

RFQ field

Input beam current

Output beam current

2 3 4 5 6 7 8-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Energy(MeV)

a.u

.

0 50 100 150 200 250 300-0.2

0

0.2

0.4

0.6

0.8

1

1.2

y vs. xfit 1

Al thickness (µm)

Tran

smis

sio

n

Energy (MeV)

a. u

.

- beam transmission in increasing thickness Al absorbers . - curve fit by smoothing spline- first derivative for range distribution. - energy spectrum from relation energy- range

0 50 100 150 200 250 300 350-0.005

0

0.005

0.01

0.015

0.02

0.025

0.03

Al thickness (µm)

Proton beam transport: propagation in the complete DOFO-like channel

(9PMQs) mounted on the SCDTL (RF off)

After 10h of conditioning it has been possible to feed the structure with a forward power of 0.9 MW.

Signal acquired from power meter with EPM-P probe controlled via GPIB: (left) reflected power, (right) forward power.

- The SCDTL-1 structure has been coupled to the high power RF line coming from a TH2090 Klystron (Pmax=15MW); - the pulse lenght (flat top) is 3.5 μs;- the repetition rate available is only 6.25 Hz;- the total attenuation was 97.7 dB: 57.7 from a WR284 Thomson directional coupler and further 40 dB with cable attenuators.

RF hot tests

Spessore (d) 1.4 mm

Lunghezza 40 mm

Lunghezza efficace (Leff) 3 cm

Numero di avvolgimenti (N) 9

Simple characterization method of small high gradient permanent magnet quadrupoles

11

0 )sin()cos(n

nn

n nwtbnwtaaV

)4/(2 rifeff RdLNTcG

22

222 bac

21 /5.0 ccRr rif

21

211 bac

R rif = 0 mm R rif = 1 mm

Thanks for your attention