Transcript Diapositiva 1
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)
VARIABLE CURRENT 30keV SOURCE RFQ SCDTL-1
TOP - IMPLART Project
VERTICAL LINE TERMINAL 3 – 7 MeV DTL HORIZONTAL LINE EXTRACTIONS PMQ 7mm 3cm
Outline
•
Experimental results with low energy (3-7 MeV) proton beams: - Radiobiological experiments - LiF detectors development - Porous Silicon for micromachining
•
Experimental results on the first SCDTL module (7-11.6 MeV): - 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
•
Simple characterization method of small high gradient permanent magnet quadrupoles (PMQs)
Experimental results with low energy (3-7 MeV) proton beams
Low
proton fluences (10 6 protons/cm 2 ): VERTICAL BEAM LINE
Low fluences
for the study of in vitro models of cellular mechanisms involved in the carcinogenesis process development
Q 1 Q 2 Magnet 90° High
fluences (> 10 10 protons/cm 2 ): HORIZONTAL BEAM LINE
Q 1 Q 2 Q 3 Q 4 High fluences
to develop a LiF particle detector and to realize porous silicon for Micro-Electro Mechanical-Systems (MEMS)
Radiobiological experiments
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) Dosimetric control: GafChromic films EBT3 suitably calibrated at LNL Laboratories. The irradiated area has a uniformity of 90%
Beam characteristics during V79 cells irradiation MeV 5 Prot/cm2 10 11 -10 15 μA 0.16
μs 13 Hz 6.25
Gy/min 2
Cells with their culture liquid (6μm thickness), in a cylindrical sample holder with a diameter of 13 mm Mylar sheet (50μm thickness) Kapton window 50 m thick Au scattere 2 m thick Al collimator 2mm diameter
The dose response curve obtained was in agreement with literature data
LiF detectors development Energy (MeV) 3 - 7 Fluence range 10 11 - 10 15 Sample LiF films (1μm thickness) LiF crystals
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.
F ed F luminescono nel rosso
Porous Silicon for Micro-Electro-Mechanical Systems Silicon Bulk Micromachining Energy (MeV) 1.8
Fluence (prot/cm 2 ) 10 14 – 10 15 Sample 1.5 x 1.5 cm 2 p-type silicon Pattern Molybdenum mask to doped with Boron (100) - 1 10 Ohm*cm
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 31 µm (corrisponding to the stopping range of 1.8
MeV) because of the imaging angle (67 °).
transfer patterns on silicon FESEM Analysis (Field Emission Scanning Electron Microscope)
Transferred pattern after porous silicon removal Experimental setup used to irradiate silicon sample
Experimental results on the first SCDTL module (7-11.6 MeV) RF cold test:
the structure has been tuned and completely characterized on RF bench SCDTL24aprile 3.06
3.04
3.02
w1(GHz)= 3.01077
w2(GHz)= 2.99238
k= 0.02872
k1= -0.00927
k2= 0.00357
Stop Band(GHz)= 0.00081
3 2.98
2.96
0 0.2
0.4
0.6
phi (pi units) 0.8
1 The measured modes dispersion curve Smith chart showing the coupling of the π/2 mode MARK Freq=2997.635 MHz Val=-19.073 Fmin=2997.64
Q reflection measurement -2 -4 -6 -8 -10 -12 -14 -16 -18 Tuners for tuning coupling acceleranting tanks 3000 cavity and flattening the field Resonant modes measured in reflection from the central tank Holes for pickups Bead pull measurement: squared electric field along the axis on the SCDTL structure
Fluorescent target
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)
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 Einzel voltage, kV Q1 Gradient, T/m Q2 Gradient, T/m Q3 Gradient, T/m Q4 Gradient, T/m 28.2
27.8
-9.1
8.87
-10.15
12.02
The final beam spot on a fluorescent target (included within a diameter of 4mm)
Input beam current
Proton beam transport: propagation in the complete DOFO-like channel (9PMQs) mounted on the SCDTL (RF off)
Arc current 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: DTL field RFQ field Output beam current • to residual misalignements • mainly to the presence of a low energy satellite in the input beam.
- beam transmission in increasing thickness Al absorbers . - curve fit by smoothing spline - first derivative for range distribution. - energy spectrum from relation energy- range
1.2
1 0.8
0.6
0.4
0.2
0 -0.2
0 50 100 150 Al thickness 200 (µm) 250 y vs. x fit 1 300 0.03
0.025
0.02
0.015
0.01
0.005
0 -0.005
0 50 1.2
1 0.8
0.6
0.4
0.2
100 150 200 Al thickness 250 (µm) 300 0 350 -0.2
2 3 4 5 6 7 8
RF hot tests
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 (P max =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.
Simple characterization method of small high gradient permanent magnet quadrupoles
Spessore (d) Lunghezza Lunghezza efficace (L eff ) Numero di avvolgimenti (N)
r
0 .
5
R rif c
1 /
c
2
1.4 mm 40 mm 3 cm 9
V c
1
a
R rif = 0 mm R
rif = 1 mm
0
a
1 2
n
1
a b
1 2
n
cos(
G
c
2
T
/(
N
4
L eff d
R rif
)
nwt c
2 )
n
1
b n
sin(
a
2 2
b
2 2
nwt
)