DAFNE Upgrade Status

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DAFNE Upgrade Status
David Alesini, LNF-INFN For the DA?NE 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)
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OUTLINE

• DA?NE 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

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FROM DA?NE TO DA?NE UPGRADE
DAFNE PARAMETERS (KLOE RUN) DAFNE PARAMETERS (KLOE RUN)
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
?Piwinskiqcross?z / ?x 0.45
L (cm-2s-1) 1.5 x1032
I-_at_LMAX (A) ?1.5
I_at_LMAX (A) ?1.1
e
e-
KLOE

• In case of colliders with small Piwinsky angle _at_
  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 ?yMIN??z and one has to reduce
  ?z also
• ? This can intruduce problems of High Order Mode
  heating, coherent synchrotron radiation, RF power
  consumption and instabilities.

Overlap area _at_ IP
y
? Other possibilities to increase the luminosity
are the introduction of crab cavities (testing in
KEKB) or round beams (testing in VEPP2000).
?y
z
?z
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NEW COLLISION SCHEME (P. Raimondi, 2006)

1. Large Piwinskis angle ?Pq?z / ?x

1. Geometric luminosity gain
2. Very low horizontal tune shift
3. No parasitic collisions

2. ?y comp. with overlap area (?y ??x /?)

1. Geometric luminosity gain
2. Lower vertical tune shift
3. Vertical tune shift decreases with oscillation
   amplitude
4. Suppression of vertical synchro-betatron
   resonances

3. Crab waist transformation (realized with
two sextupoles)

1. Geometric luminosity gain
2. Suppression of X-Y betatron and synchro-betatron
   resonances

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BEAM PROFILES _at_IP AND NEW PARAMETERS
DAFNE (KLOE run)
DAFNE (KLOE run) DAFNE Upgrade
Ibunch (mA) 13 13
Nbunch 110 110
by (cm) 1.7 0.65
bx (cm) 170 20
sy (mm) 7 2.6
sx (mm) 700 200
sz (mm) 25 20
qcross (mrad) (half) 12.5 25
FPiwinski 0.45 2.5
L (cm-2s-1) 1.5x1032 gt5x1032
DAFNE Upgrade
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NEW IR LAYOUT (1/2)
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NEW IR LAYOUT (2/2)
Old layout
splitters removed
New dipoles positions
New layout
new vacuum chambers _at_ IP
Crab sextupoles
10 m
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IP FOR SIDDHARTA EXPERIMENT
IP
5.5cm

• Aluminum

• Window thickness 0.3 mm

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IP LAYOUT AND LUMINOSITY MONITORS
SIDDHARTA
K monitor
Bhabha calorimeter
? monitor
GEM Bhabha Monitor
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IP LAYOUT AND LUMINOSITY MONITORS
SIDDHARTA
K monitor
Bhabha calorimeter
? monitor
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NEW IR2 CHAMBER LAYOUT (1/2)
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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)

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NEW FAST INJECTION KICKERS (1/2)
IP1
e
e-
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NEW FAST INJECTION KICKERS (2/2)
VT
60 bunches
t
Present pulse length 200ns
2 striplines with tapered elliptical cross section
VT
Strip ceramic supports
3 bunches
BEAM
t

• EXPECTED BENEFITS
• higher maximum stored currents
• Improved stability of colliding beams during
  injection
• less background allowing data acquisition during
  injection

pulse length 6 ns

• KICKERS PECULIARITIES
• 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.

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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

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DA?NE COMMISSIONING MILESTONES

• Commissioning started at the end of November
• Both beams stored in the first days of December
• 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 Luminosity Bhabha monitor
  installation
• 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

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.
The new rings layout is 10 cm shorter than the
original one.
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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 (k0.5 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
• ()

Ex. OF VERTICAL BEAM BEAM SCAN
Very good knowledge of the machine linear model
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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
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HIGH CURRENT OPERATION (1/2)
Achieved 1200mA e- and 960mA e (single beam)

• Specific Luminosity is 34 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
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HIGH CURRENT OPERATION (2/2)
Luminosity monitors
1 day integrated luminosity
? monitors
Colliding beams
Not colliding beams (vertical separation)
K monitor
Bhabha calorimeter
Geometrical luminosity monitor
Within lt20 all monitors gives consistent results
in term of luminosity
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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.
• 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.

45 kV
5 ns
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BUNCH LENGTH MEASUREMENTS
e
e-
Machine impedance reduction of about 30
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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