DAFNE Upgrade Status
David Alesini, LNF-INFN
For the DAFNE Upgrade and Commissioning Team (*)
(*) David Alesini, Maria Enrica Biagini, Caterina Biscari, Roberto Boni, Manuela Boscolo, Fabio Bossi, Bruno Buonomo,
Alberto Clozza, Giovanni Delle Monache, Theo Demma, Enrico Di Pasquale, Giampiero Di Pirro, Alessandro Drago,
Alessandro Gallo, Andrea Ghigo, Susanna Guiducci, Carlo Ligi, Fabio Marcellini, Giovanni Mazzitelli, Catia Milardi,
Fabrizio Murtas, Luigi Pellegrino, Miro Preger, Lina Quintieri, Pantaleo Raimondi, Ruggero Ricci, Ugo Rotundo, Claudio
Sanelli, Mario Serio, Francesco Sgamma, Bruno Spataro, Alessandro Stecchi, Angelo Stella, Sandro Tomassini, Cristina
Vaccarezza, Mikhail Zobov (INFN/LNF, Frascati (Roma)), Ivan Koop, Evgeny Levichev, Pavel Piminov, Dmitry Shatilov
(BINP SB RAS, Novosibirsk), Victor Smaluk (BINP, Novosibirsk), Simona Bettoni (CERN, Geneva), Marco Schioppa (INFN
Gruppo di Cosenza, Arcavacata di Rende (Cosenza)), Paolo Valente (INFN-Roma, Roma), Kazuhito Ohmi (KEK, Ibaraki),
Nicolas Arnaud, Dominique Breton, Patrick Roudeau, Achille Stocchi, Alessandro Variola, Benoit Francis Viaud (LAL,
Orsay), Marco Esposito (Rome University La Sapienza, Roma), Eugenio Paoloni (University of Pisa and INFN, Pisa),
Paolo Branchini (Roma3, Rome)
OUTLINE
1) DAFNE UPGRADE:
 New IR implementing the large Piwinsky angle and crab
waist collision scheme
 New fast injection kickers
 New low impedance bellows
2) STATUS
 Commissioning milestones
 Best machine performances at high current
 Fast pulsers performances
 Bunch length measurements
 Open problems and strategies for machine optimization
FROM DAFNE TO DAFNE UPGRADE
e+
KLOE
DAFNE PARAMETERS
(KLOE RUN)
e-
Ibunch (mA)
13
Nbunch
110
 y* (cm)
1.7
 x* (cm)
170
y* (mm)
7
x* (mm)
700
z (cm)
2.5
cross (mrad) (half)
12.5
FPiwinski=crossz / x
0.45
L (cm-2s-1)
1.5 x1032
I-@LMAX (A)
1.5
I+@LMAX (A)
1.1
 In case of colliders with small Piwinsky angle @ IR, the key
parameter to increase the luminosity is the reduction of the y* and the
increase of stored currents;
 To avoid luminosity reduction because of the hourglass effect
y*MINz and one has to reduce z also;
Overlap
area @ IP
y
 This can intruduce problems of High Order Mode heating, coherent
synchrotron radiation, RF power consumption and instabilities.
 Other possibilities to increase the luminosity are the introduction of
crab cavities (testing in KEKB) or round beams (testing in
VEPP2000).
y*
z
z
NEW COLLISION SCHEME
1. Large Piwinski’s angle FP=z / x
a) Geometric luminosity gain
b) Very low horizontal tune shift
c) No parasitic collisions
2. y* comp. with overlap area (y* x /)
d) Geometric luminosity gain
e) Lower vertical tune shift
f)
Vertical tune shift decreases with
oscillation amplitude
g) Suppression of vertical synchrobetatron resonances
3. Crab waist transformation
(realized with two sextupoles)
h) Geometric luminosity gain
i)
Suppression of X-Y betatron and
synchro-betatron resonances
(P. Raimondi, 2006)
BEAM PROFILES @IP AND NEW PARAMETERS
DAFNE (KLOE run)
DAFNE Upgrade
DAFNE
(KLOE run)
DAFNE
Upgrade
Ibunch (mA)
13
13
Nbunch
110
110
y* (cm)
1.7
0.65
x* (cm)
170
20
y* (mm)
7
2.6
x* (mm)
700
200
z (mm)
25
20
cross (mrad) (half)
12.5
25
FPiwinski
0.45
2.5
L (cm-2s-1)
1.5x1032
>5x1032
NEW IR LAYOUT (1/2)
NEW IR LAYOUT (2/2)
Old layout
splitters removed
New dipoles
positions
New layout
new vacuum
chambers @ IP
Crab sextupoles
~10 m
IP FOR SIDDHARTA EXPERIMENT
IP
5.5cm
• Aluminum
•Window thickness 0.3 mm
IP LAYOUT AND LUMINOSITY MONITORS
SIDDHARTA
K monitor
Bhabha
calorimeter
 monitor
GEM Bhabha
Monitor
IP LAYOUT AND LUMINOSITY MONITORS
SIDDHARTA
K monitor
Bhabha
calorimeter
 monitor
NEW IR2 CHAMBER LAYOUT (1/2)
NEW IR2 CHAMBER LAYOUT (2/2)
• IR2 region symmetric with respect to IR1 (Possibility to swap the
machine to change IP position);
• “Half Moon” chamber allows complete beam separation (no 2nd IP)
NEW FAST INJECTION KICKERS (1/2)
IP1
e+
e-
NEW FAST INJECTION KICKERS (2/2)
VT
60 bunches
Present pulse length ~200ns
t
2 striplines with
tapered elliptical
cross section
VT
Strip ceramic
supports
3 bunches
t
pulse length ~6 ns
KICKERS PECULIARITIES
BEAM
EXPECTED BENEFITS
•higher maximum stored currents;
• The new kickers can be feed by the old pulsers
(200 ns) or by the new pulsers (6 ns);
• They have a beam coupling impedance and
HOM content much lower with respect to the
previous ones;
•The design, slightly modified, can be adopted
also for the ILC damping ring.
•Improved stability of colliding beams during
injection;
•less background allowing data acquisition
during injection;
NEW BELLOWS
OLD BELLOW
• 6 new bellows for each ring;
• Shielding based on Be-Cu  strips 0.2 mm
thickness;
•lower impedance and better mechanical
performances;
DAFNE COMMISSIONING MILESTONES
• Commissioning started at the end of November
• Both beams
December
stored
in
the
first
days
of
• Low- optics applied in January and first
collisions
• First week of February solenoid winding installed
in the MRp and 800 mA stored for the first time
after the upgrade (special pattern)
• February Crab-Waist sextupoles in operation
• February 11th
installation
Luminosity
Bhabha
monitor
• Beginning of March first L ~ 1032 is measured
• March the 10th SIDDHARTA installation
• First half of March new transverse horizontal
feedback installed in the MRe ring
The
new
rings
layout is ~10 cm
shorter than the
original one.
As a consequence, the
frequencies of the MR and
DR RF cavities has been
changed by changing the
tuner operation point.
Since the DR length has not
been reduced a new DR
optics configuration and
orbit has been calculated
and implemented.
LINEAR OPTICS MODEL OPTIMIZATION
Measured -functions and dispersion compared with
the optics model
 Orbits in the machine have been optimized and
some elements re-aligned.
 Linear optics model has been optimized
comparing the
measurement results (tunes, functions, dispersion,..) with the theoretical ones.
 XY coupling has been corrected by rotating the
permanent quads (k=0.5% reached in both rings).
 Also the permanents quadrupoles and crab
sextupoles longitudinal positions have been optimized
to match the crab wais conditions.
 Positions of the quadrupoles in IP2 have been
changed to improve the beam stay clear
 (…)
 y  4mm
Ex. OF VERTICAL BEAM BEAM SCAN

2
 25mrd

2
 27mrd
 x*  0.266m
 y*  9mm
Very good knowledge of the machine linear model
 x  0.26mm  mrad
 x  5.1050  y  5.1850
 x  5.0950  y  5.1650
EFFECTS OF CRAB SEXTUPOLES ON LUMINOSITY
LUMINOMETERS
A huge work on machine optimization has been done
and is still in progress in term of feedbacks systems
tuning, background minimization and tuning of the
machine luminosity…
Crab on
Crab off
Transverse beam dimensions at
the Synchrotron Light Monitors
HIGH CURRENT OPERATION (1/2)
Achieved 1200mA e- and 960mA e+ (single beam)
• Specific Luminosity is 3÷4 times higher
than during the past best runs, as
expected.
 exhibit a linear behavior
• Lpeak21032
Achieved 1200mA e- and 850mA e+ in collision,
max simultaneous about 700mA against 700 mA
HIGH CURRENT OPERATION (2/2)
Luminosity monitors
Within <20% all monitors
gives consistent results in
term of luminosity
Geometrical
luminosity
monitor
Bhabha
calorimeter
 monitors
1 day integrated luminosity
Colliding beams
Not colliding beams
(vertical separation)
K monitor
TEST OF FAST PULSERS WITH NEW KICKERS
25 kV
200 ns
 The new kickers can be feed by the old pulsers
(200 ns) or by the new pulsers (6 ns).
 First test on e+ ring with fast pulsers have
been successfully done.
45 kV
 Unfortunately we had problems with the new
fast FID pulsers after few hours of operation.
They have been now recovered and ready to be
re-installed.
5 ns
BUNCH LENGTH MEASUREMENTS
e+
e-
FWHM/2.36 [cm]
3
130kV, new, FWHM/2.36
4
with ICE
130kV, old, FWHM/2.36

130kV,upgrade,FWHM/2.36
3,5
2,5
without ICE

3
2
2,5
upgrade
1,5
2
1
1,5
I [mA]
0,5
0
10
20
30
40
50
I [mA]
1
0
5
10
15
Machine impedance reduction of about 30%
20
25
30
35
CONCLUSIONS, OPEN PROBLEMS AND STRATEGIES
-Good operation with crab sextupoles (test of crab waist concept);
-Good knowledge of the machine optics model;
-Reached the coupling goal of 0.5%;
-Good vacuum conditioning;
-Achieved 1200 mA e- and 960 mA e+ and 1200mA e- and 850mA e+ in collision with a peak
luminosity of 21032  a continuous optimization is in progress;
-Bunch lengths measurements show a shorter bunch due to lower machine impedance;
-Fast kickers test done with success  we need to go in continuous operation with the new
pulsers;
-No “hard to fix” problems found so far  a lot of “single pieces” are working very nicely, need
to put all together at the same time;
-Commissioning rate a factor 2 slower than hoped;
-Beam lifetimes need dynamics aperture optimization
-Background optimization has been done  and is further necessary for the SIDDHARTA
experiment