Heinz-Dieter Nuhn – LCLS Undulator Group Leader May 14, 2009 Undulator Plans Heinz-Dieter Nuhn – LCLS Undulator Group Leader May 14, 2009

25 Undulators Installed

Answers to Committee Questions What in project scope activities remain for LCLS undulators? ANSWER: There are 5 undulators more to be tuned, a total of 8 undulators to be installed. There are also ANL BLMs in scope which need to be made. What improvements can you anticipate in the area of undulators and undulator diagnostics for LCLS looking ahead to operations? ANSWER: Upgrade of signal processing for existing BLMs to add integration capability. K-vs-temperature calibration for undulator segments to improve the estimate of undulator K values at deviating temperatures. Procurement of precision temperature sensors for undulator segments. Procurement of additional ANL-Style BLMs (under consideration) some additional are now in scope, a full complement would need an addition to scope.

Answers to Committee Questions Can you present a summary of ‘Lessons Learned’ from the undulator construction activities supporting LCLS? ANSWER: Tuned Undulators were initially stored in an uncontrolled temperature storage area (building 750 pit, ). We ended up re-tuning all undulators. Since we had no data and mechanical calculations would have been too complicated and expensive, we should have tested the temperature limit of undulators. Interference fit of undulator shims and vacuum chamber occurred this was due to many design iterations of vacuum chamber. This should have been discovered at fully integrated model. Heavier bolts should have been used to hold the pole assemblies to the titanium strong back. Undulator feet design should have been finalized during final design review and not during measurement and implementation stage. Longitudinal thermal expansion was not considered. Temperature excursions caused big problems for us. Canted poles are a great idea. Without them, we would not have been able to set K to 0.015 %, i.e., we would not have been able to set the gap to 0.9 µm with parallel poles. Spending money on a good measurements lab is essential. We have had to overcome many unnecessary obstacles such as air conditioner failures, air compressor failures, space constraints, bad cranes, etc. These take up a lot of time and energy.

Girder Position / Temperature Stability Temperature fluctuations and ground motion cause changes in Undulator strength, which depends on Temperature Beam trajectory Electron beam trajectory (phase errors) due to Quadrupole position instability Observed stability of girder positions and temperatures is better than expected.

Temperature at All Girders Upstream U23 Center U23 Downstream U23 On Girder Mounted to Undulator

Temperature Recording Girder 16 SHUT DOWN (UND INSTALLATION) REPAIR OPPORTUNITY DAY (ROD) HVAC SETPOINT ADJUSTMENT 50 mK

Girder 15 Movement (18 h) During ROD (11 h) Mechanical Hysteresis >1 µm

Girder 13 Stability During 19h Operation 200 nm

Girder Stability During 2008 Winter Break RMS Position Change < 1 µm Courtesy of Franz Peters

K Adjusted for Temperature Deviations

Use of (T-)Corrected K Values TEMPERATURE CORRECTED K K ADJUSTMENT RANGE TAPER REQUIREMENT

Radiation Control and Monitoring Undulator radiation damage is greatly reduced through Machine Protection System (MPS) hardware interlocks that inhibit beam to the undulator hall when PEP/ANL type BLM signals are above threshold Beam loss fiber signals are above threshold Horizontal and/or vertical trajectory is outside ±1mm Comparator toroids indicate beam loss. Any of the upstream profile monitors is inserted More than 1 BFW is inserted or a BFW is moving A regular TLD monitoring program is in place (s. below) A regular undulator replacement program will start soon (s. below)

TLD Readings at First Undulator LOCATION WEEK 1 PHOTON [rem] WEEK 2 PHOTON [rem] WEEK 3 PHOTON [rem] U25:ANL-BLM 0.081 0.106 0.051 U25: PEP-BLM 0.042 0.048 0.030 U25: Back +X 0.065 0.008 0.033 U25: Back +Y 0.012 0.071 0.064 U25: Back -X 0.039 0.026 0.029 U25: Back+Y 0.013 0.014 U25: Front +X 0.112 0.093 0.072 U25: Front +Y 0.217 0.105 0.110 U25: Front -X 0.046 0.055 0.025 U25: Front -Y 0.141 0.123

Dose During Initial X-Ray Operation e-folding length 8.7 m Increased TLD Readings are expected to be predominantly low energy synchrotron radiation, not to cause significant magnet damage

TLD Replacement Program Thermo Luminescent Dosimeters (TLDs) are mounted inside the Undulator Hall and are regularly replaced and evaluated Baseline 10/3/2008 – 12/9/2008 (10 TLDs) Startup 12/12/2008 – 12/17/2008 (12 TLDs) 1st Undulator 1/28/2009 – 2/4/2009 (15 TLDs) 1st Undulator 2/4/2009 – 2/11/2009 (14 TLDs) 1st Undulator 2/11/2009 – 2/18/2009 (18 TLDs) 1st Undulator 2/18/2009 – 3/2/2009 (48 TLDs) FEL Operation 3/24/2009 – 4/22/2009 (68 TLDs) FEL Operation 4/22/2009 – 5/6/2009 (125 TLDs) FEL Operation 5/6/2009 – … (128 TLDs) FEL Operation … Latest TLD placements include detection of neutrons and high energy gamma through use of moderators and Ti and Pb absorbers. TLD volume is expected to taper down after initial observation period.

Undulator Replacement Program Undulators will be periodically removed from the Undulator Hall to be re-measured at the MMF to check for radiation damage. A “test”-undulator was re-measured after several weeks of beam operation. No damage was found. First undulator that participated in FEL run is scheduled for re-measuring in June. Depending on MMF availability, up to 2 undulators per month will be removed from the Undulator Hall for checking. After the undulators have been found undamaged they will be reinstalled onto the original girder.

Summary Undulator tuning and installation close to completion Temperature and girder stability well within tolerance Beam loss control and radiation monitoring is in place High radiation levels at initial FEL operation are expected to be predominantly low energy photons that should not generate demagnetization Electronics components may need additional shielding Undulator replacement program will start soon

End of Presentation