Sub-Task 12.4.1:
Progress and Plans for
Experimental Measurements
Nicoleta Baboi, Liangliang Shi, Thomas Wamsat
18. December 2013
Aim
> HOM-based beam diagnostics
for the European XFEL
 1. Beam phase in 1.3 GHz cavities
 2. Beam position in 1.3 GHz cavities
 3. Beam position in 3.9 GHz cavities
> Previous experience and status
 1. Proof-of-principle made
New electronics from Samer Bou Habib (WUT/DESY) under lab tests
Early next year to be tested in FLASH
 2. Electronics from SLAC installed at 40 cavities in FLASH
Proof-of-Principle; calibrated into beam position
But the calibration is unstable → need study
 3. Prototype electronics from FNAL has been tested at FLASH (4 cavities)
Specs were defined (for FLASH/FNAL and XFEL/DESY electronics)
Also calibration unstable → need study
Task 12.4.1, DESY
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EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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FLASH
European XFEL
1.3 GHz Cavities
- Electronics installed in 40 cavities
(SLAC/CEA/DESY)
- Raw signals used for beam
centering
- EuCARD2: Unstable calibration
(phase or even frequency drifts?)
- Electronics under design, based
on same frequency as for FLASH
(WUT/DESY)
3.9 GHz Cavities
Status and Plans for
HOM-based Beam Position Monitoring (HOMBPM)
- Theoretical and experimental
studies (EuCARD: UROS, UMAN,
DESY together with FNAL)
- Defined specs for HOMBPM
electronics (also for XFEL)
- Electronics under construction
(FNAL), to be installed and
tested/commissioned this autumn
- EuCARD2: Unstable calibration
(same problem as for 1.3 GHz?)
- Electronics under design, based
on same frequency ranges as for
FLASH (DESY)
- But much more challenging:
Task 12.4.1, DESY
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8 coupled cavities cf. 4
4.5 cf 1 MHz bunch frequency
Different orientation of cavities
- EuCARD2: Need significant
theoretical and experimental
studies
EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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FLASH
European XFEL
1.3 GHz Cavities
- Proof-Of-Principle made
(SLAC/CEA/DESY)
- Electronics under design (same as
for XFEL HOMBPM, WUT/DESY)
- EuCARD2: experimental studies
- Same as for FLASH
3.9 GHz Cavities
Status and Plans for
HOM-phase Beam Phase Monitoring
- So far no isolated monopole mode
identified, which could be used for
phase monitoring
- Theoretical (and experimental)
studies (lower priority in EuCARD2)
Task 12.4.1, DESY
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- Same as for FLASH
EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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Milestones and XFEL Schedule
> Milestones
 Completed characterisation of HOMs in the 8-cavity XFEL 3HC module M24
Maybe delays: 3.9 GHz module expected towards end of 2014
 Cold S21 measurements on XFEL modules performed
First 1.3 GHz module expected middle of 2014
M24
> FLASH:
 2014: only user run -> only parasitical measurements possible
> XFEL-Injector commissioning planned to start in Spring 2015
 Start measurements with beam (probably only parasitical)
Task 12.4.1, DESY
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EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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PhD work
> Personal status:
September-December 2013: mainly for literature study.
 Joined two schools:
1. Joint US-CERN-Japan-Russia International Accelerator School at
Shizuoka, Japan, October 23-31, 2013.(Mainly focused on general
accelerator physics: basic beam dynamics, storage ring, insertion
devices etc. )
2. Eighth International Accelerator School for Linear Colliders, Antalya,
Turkey, Dec 4-16,2013.(Mainly focused on accelerator technology:
room temperature RF, superconducting RF, LLRF&HPRF etc.)
 Self study and discussion
Task 12.4.1, DESY
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EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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DOOCS
Courtesy of DESY
Task 12.4.1, DESY
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EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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Plan
> To find out the reason for calibration instability
 Beam Position--taking data at FLASH(1.3 GHz cavity) including
35 cavities at both HOM ports and all BPMs along the linac.
3.9 GHz cavity electronics will come soon from Fermilab.
 Beam Phase– electronics will be ready soon for 1.3GHz cavity (XFEL)
from WUT/DESY. It gives 1.3, 2.4 GHz for beam phase monitoring and
1.7 for position monitoring.
 For both position and phase measurements, the challenging part is
3.9 module (8 cavities) for XFEL.
 Data will be analyzed first with SVD method.
 Spring of 2015, the XFEL will start operation including (5 1.3GHz
modules and one 3.9 GHz module)
Task 12.4.1, DESY
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EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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Look for calibration instability
> Data from ACC1 cavity3, date:18 Nov,2013
Task 12.4.1, DESY
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EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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Page 9
Distinguished Performance Award at the LC School
Task 12.4.1, DESY
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EuCARD2 Task12.4 Online-Meeting
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18 Dec. 2013
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Page 10