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ACC-OTHERS-01 GSI SCIENTIFIC REPORT 2009
tion. Finally, the design value of 8.0 keV/u was kept.
Transmissions along the RFQ up to 60 % were reached
for H3 + as well as for C 4+ beams for matched injection.
For a detailed summary of RFQ commissioning results
see Ref. [8].
420
415
410
405
400
395
H3+ - full - 8.0keV/u
H3+ - probe - 8.0keV/u
H3+ - full - 8.5keV/u
H3+ - probe - 8.5keV/u
C4+ - full - 8.0keV/u
390
4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4
tank voltage [V]
Figure 3: RFQ output beam energy in keV/u as function
of the scaled tank voltage for different ion beams
IH Linac
More than 140 measurement series including numerous
amplitude and phase scans were performed with the IH
linac. Different LEBT beam energies, RFQ settings, and
IH tank plunger configurations were investigated. The
linac was optimized with respect to high beam transmission,
minimum beam emittances and optimized bunch
signal amplitudes. For the final setting, the measured
linac beam energy amounts to 7.2 MeV/u at a RF pulse
power of 910 – 930 kW.
Table 2: Typical beam currents and linac transmission
Ion
Species
C 4+ / C 6+
H 3 + / p
Beam Current / µA Linac Trans-
LEBT Linac Stripped mission
~170 ~80 115 48 %
1100 400 1200 39 %
710 307 900 46 %
Figure 4: Measured C 4+ / C 6+ beam pulses
Table 2 summarizes typical beam currents achieved at
the LEBT upstream of the solenoid focusing into the
RFQ, behind the IH linac, and behind the stripping foil.
160
LEBT: 169 µA
Linac: 85.9 µA
Stripped: 116 µA
Fig. 4 shows examples of measured beam pulses. A total
linac transmission (incl. solenoid, RFQ, and IH linac) up
to 48 % was achieved, meeting the design beam currents
behind the stripper (100 – 120 µA for C 6+ and 700 µA for
protons) and even exceeding them.
The quadrupole settings behind the linac were optimized
to achieve minimum beam diameters at the stripping
foil in order to reduce emittance growth effects in
the foils. Measured beam emittances for the final settings
are listed in Table 3 and are shown in Fig. 5. Twiss parameters
are similar in both transverse planes.
Figure 5: Hor. (left) and ver. (right) proton beam emittances
measured ~1 m behind the stripping foil
Table 3: Measured beam emittances (4 × rms for 90 % of
the beam current) behind the stripping foil and emittance
growth in the foil
Ion
Species
ε 4×rms, 90% / π mm mrad
horizontal vertical
Emittance Growth
hor. ver.
C 6+ 3.6 3.0 6 % 6 %
protons 4.7 4.7 15 % 40 %
Summary and Outlook
Commissioning and beam tests of all components delivered
and supervised, respectively, by GSI were accomplished
successfully in 2009. Design beam currents were
achieved and even exceeded; the measured beam emittances
agree well with expected values. Finally, twenty
CNAO operators, engineers and physicists were trained in
linac operation by GSI in November 2009 – marking the
end of the GSI services fixed in the CNAO-GSI contract.
Acknowledgements
The authors wish to thank the numerous GSI colleagues
involved in this project over the past years. Their efforts
are greatly acknowledged. Many thanks to all CNAO and
INFN collaborators for the fruitful cooperation, the cordial
atmosphere and the great hospitality at CNAO.
References
[1] S. Rossi, EPAC 2006, p. 3631.
[2] B. Schlitt, LINAC08, p. 720.
[3] B. Schlitt et al., GSI Scientific Report 2006, p. 383.
[4] A. Reiter et al., EPAC 2006, p. 1028.
[5] H. Vormann et al., EPAC08, p. 1833.
[6] B. Schlitt et al., GSI Scientific Report 2008, p. 409.
[7] E. Bressi et al., PAC09, TU6PFP005.
[8] P. Posocco et al., HIAT09, in print.