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Monochromatic beam is delivered by a large-offset fixed-exit monochromator located in the optics hutch. There are two main reasons for using a large downward-offset monochromator. First, there is only 5 mrad horizontal angle between the canted undulator beamlines P02 and P03.  The compact arrangement of the two beamlines can be achieved by shifting one of the two beamlines in the vertical direction. This is done by using a so-called large-offset monochromator at the P03 beamline. The second issue is the stability of the installation, especially when the photon beam extent is within a range of a few square micrometers. By having an X-ray beam at a height of 900 mm above the floor (instead of 1400 mm) in the endstations, we significantly reduce the amplitudes of potential (mechanical) vibrations.

The monochromator is equipped with a pair of cryocooled silicon (111) crystals having a vertical offset of 490 mm downward. The energy can be varied from 8 to 23 keV with a resolution of ΔE/E ≃ 10−4. A scheme of the main optic components of the beamline is given in Fig. 1. In addition, a pair of multilayers is under design. The latter option will be especially useful for nanofocus and µUSAXS applications owing to the higher flux provided by the pink beam. In this latter configuration an energy resolution of ΔE/E ≃ 0.5 × 10−2 is expected at the fixed energies of 10 keV and 13 keV.

A planar double mirror (reflection angle = 2.27 mrad, vertical offset = 10 mm downward) located in the optics hutch past the monochromator is used to suppress higher harmonics. Three different coatings are available: a SiO2 coating for the energy range 8–12 keV, a molybdenum (Mo) coating for the energy range 12–18 keV, and a palladium (Pd) coating for the energy range 18–23 keV. The theoretical curves in Fig. 2 show the calculated suppression of higher harmonics.


The LOM500 is the Large Offset Monochromator used at P03.

LOM500: Geometry

 

Figure 1a Schematic drawing of the Large Offset Monochromator at P03: When using no mirror, the vertical offset between the two crystals has to be 500 mm.

 

Figure 1b Schematic drawing of the Large Offset Monochromator at P03: When using mirrors, the vertical offset between the two crystals has to be 490 mm.



LOM500: Computer

  • Connect to LOM500 computer via remote desktop

> Computer name: haspp03lom > Login: ad2 > Password: ***********

  • Start LOM500-System.tsm
  • Start LOM500-Control-1.pro
  • Press F11 (einloggen)
  • Press F5 (start)

LOM500: Energy tuning

Si(111)

The interplane distance for Si(111) is 0.31355 nm. Table 1  gives the Bragg angle values and pitch values of the Si(111) crystals for different X-ray energies. Zero position of the crystals  corresponds to 7o (as shown in Fig. 1a and Fig. 1b) so that:

pitch = θB 7

The values in online are corrected for this 7 degrees whilst in the LOM Twincat program not.

How to change the energy

0. Place the SESO at 13 keV on the Laser and mark beam position on screen. 

1. Change the angle of the first crystal according to the selected energy (LOM1PITCH).

2. Adjust the undulator gap value according to the selected energy/harmonic. See U29-undulator for more details. For fine tuning of undulator gap and/or first crystal angle, use the LM2 screen.

3. Do not forget to translate the second crystal (LOM2LIN motor). 

4. Rock the second crystal angle (LOM2PITCH) around the expected angle using small (0.004 deg) scanning steps (especially when working at high x-ray energies).  You can use the Q-BPM situated in the OH as scan device (VC4). For fine tuning use the LOM2PIEZO_PITCH

5. IF necessary, adjust the beam height to the marked position (SESO) using the M2HUB 

Typical U29 gap, Bragg angle, LOM2LIN ... values can be found in Table 1

Important: beam position recommisioned in March 2015 (after 13 months shut down)

Important: LOM1HUB and LOM2HUB lose steps!!! Be carefull when moving these motors!

Table 1: How to change the energy: Typical values...

EXR [keV]HarmonicU29 gap (theo) [mm]U29 gap (exp)  [mm]θB (theo)θB1 (exp)θB2 (exp)screen pos [mm]LOM2LIN (theo) [mm]LOM2LIN (exp)  [mm]BPM_OH Int x 10-6 [a.u.]I_PETRA [mA]# bunches
10.0 121.6-11.41 --431188----
11.4 310.210.229.998 10.58 (oct 2012)9.822 (oct 2012)6213451354 (oct 2012)---
11.4 310.210.229.998 10.576 (nov 2012)9.817 (nov 2012)6413451356 (nov 2012)3.85100320
11.4 310.210.2159.998 10.578 (jan 2013)9.817 (jan 2013)6213451356 (jan 2013)2.8010060 (e-)
11.4 310.210.2159.998 10.578 (mar 2013)9.817 (mar 2013)6213451357 (mar 2013)3.15100480 (e-)
11.4 310.210.2159.998 10.578 (mar 2013)9.817 (mar 2013)6213451373.5 (mar 2013)3.058040 (e-)
11.4 310.210.2159.998 10.578 (aug 2013)9.817 (aug 2013)6213451374.5 (aug 2013)-8040 (e-)
11.4 310.210.2159.998 10.578 (aug 2013)9.8185 (aug 2013)6213451375 (aug 2013)3.358040 (e-)
11.4 310.210.2159.998 10.578 (oct 2013)9.817 (oct 2013)6213451374.5 (oct 2013)4.3010040 (e-)
12.0 3-10.569.49 10.05 (sep 2012)9.293 (sep 2012)69.614241424.0 (sep 2012)---
12.75 3-10.96-- 9.532 (may 2017)8.760 (may 2017)84---1559.5 (may 2017)0.8510040
13.0 311.311.1158.75 8.945 (oct 2011)8.655 (oct 2011)7515571535.0 (oct 2011)---
13.0 311.311.18.75 9.380 (nov 2011)8.622 (nov 2011)7515571539.0 (nov 2011)---
13.0 311.311.118.75 9.384 (may 2012)8.627 (may 2012)7515571536.0 (may 2012)---
13.0 311.311.118.75 9.384 (june 2012)8.622 (june 2012)7515571538.5 (june 2012)---
13.0 311.311.068.75 9.384 (sep 2012)8.621 (sep 2012)7515571536.0 (sep 2012)---
13.0 311.311.068.75 9.384 (jan 2013)8.628 (jan 2013)7515571536.0 (jan 2013)2.2510060 (e-)
13.0 311.311.068.75 9.384 (jan 2013)8.628 (jan 2013)7515571536.0 (jan 2013)1.708040 (e-)
13.0 311.311.068.75 9.384 (feb 2013)8.624 (feb 2013)7515571555.5 (feb 2013)1.758040 (e-)
13.0 311.311.068.75 9.384 (mar 2013)8.6232 (mar 2013)7515571556 (mar 2013)2.30100480 (e-)
13.0 311.311.068.75 9.384 (jun 2013)8.625 (jun 2013)7515571575 (jun 2013)2.20100960 (e-)
13.0 311.311.068.75 9.384 (jun 2013)8.625 (jun 2013)7515571575 (jun end 2013)2.30100960 (e-)
13.0 311.311.068.75 9.384 (aug 2013)8.626 (aug 2013)7515571576 (aug 2013)2.208040 (e-)
13.0 311.311.068.75 9.384 (aug 2013)8.6265 (aug 2013)7515571576 (aug 2013)3.0010060 (e-)
13.0 311.311.068.75 9.384 (oct 2013)8.6265 (oct 2013)7515571575 (oct 2013)3.0510040 (e-)
13.0 311.311.068.75 9.384 (nov 2013)8.622 (nov 2013)7515571575.8 (nov 2013)3100960 (e-)
13.0 311.311.048.75 9.3869 (Mar 2015)8.622 (Mar 2015)7615571576 (nov 2013)1.380960 (e-)
12.85 311.310.928.75 9.38854 (Mai 2016)8.62639 (Mai 2016)7615571574 (Mai 2016)--100960
14.0 312.211.628.11 8.755 (may 2012)7.998 (may 2012)8116851665.0 (may 2012)---
15.0 312.612.137.58 7.773 (oct 2011)7.487 (oct 2011)8818131787.0 (oct 2011)---
15.0 312.612.137.58 8.212 (may 2012)7.462 (may 2012)8818131792.0 (may 2012)---
15.0 312.612.137.58 8.212 (aug 2012)7.4515 (aug 2012)8818131794.0 (aug 2012)---
15.0 312.612.137.58 8.211 (jan 2013)7.4565 (jan 2013)8818131799.0 (jan 2013)1.03 *10060 (e-)
15.0 312.612.137.58 8.2115 (feb 2013)7.4575 (feb 2013)8818131805.0 (feb 2013)1.17 **8040 (e-)
15.0 312.612.137.58 8.2115 (feb 2013)7.4575 (feb 2013)8818131809.0 (feb 2013)1.30 **10060 (e-)
15.0 312.612.137.58 8.2115 (mar 2013)7.457 (mar 2013)8818131808.0 (mar 2013)1.40 **100480 (e-)
15.0 312.612.137.58 8.220 (Mar 2015)7.458 (Mar 2015)8818131830 (Mar 2015)-80960 (e-)
15.0 312.611.947.58 8.220 (Mai 2016)7.4668 (Mai 2016)8818131830 (Mai 2016)-100960 (e-)
15.0 312.612.017.58 8.220 (Aug 2016)7.458 (Aug 2016)9118131843.5 (Aug 2016)0.76100480 (e-)
17.0 313.513.146.68 6.879 (oct 2011)6.594 (oct 2011)9920632036.0 (oct 2011)---
17.0 313.513.1486.68 7.25 (Apr 2015)6.49 (Apr 2015)9920632109.0 (Apr 2015)-100960 (e-)
18.0 314.013.636.31 6.507 (oct 2011)6.226 (oct 2011)10421892161.0 (oct 2011)---
18.0 314.013.696.31 6.85 (nov 2013)6.103 (nov 2013)10421892248.0 (nov 2013)0.710040
18.0 314.013.696.31 6.849 (Mar 2015)6.103 (Mar 2015)10421892248.0 (nov 2013)-80960 (e-)
19.0 3-14.235.98 6.54 (nov 2012)5.789 (nov 2012)10723132342.0 (nov 2012)1.02100240
19.0 3-14.235.98 6.49 (nov 2013)5.7415 (nov 2013)10723132388.0 (nov 2013)0.65100960 (e-)
19.0 3-14.235.98 6.488 (Mar 2015)5.740 (Mar 2015)10723132388.0 (Mar 2015)-80960 (e-)
19.0 3-14.225.98 6.488 (Aug 2016)5.731 (Aug 2016)11123132413.5 (Aug 2015)0.36100480 (e-)
19.0 3-14.565.98 6.488 (Dez 2016)5.740 (Dez 2016)11123132413.5 (Aug 2015)0.1310040 (e-)
20.0 315.1-5.67 --1112443----
21.0 3-15.3- 6.387 (Mar 2015)5.637 (Mar 2015)109-2432 (Mar 2015)-80960 (e-)
 After  06.2019













* HOM not working ** HOM need to be adjusted (hub and pitch both 1 and 2)


LOM500: Cryocooling

The LOM500 is equipped with a liquid nitrogen cryocooler.

In case of alarm:

  • press SILENCE (F1) 
  • then STOP (F2)
  • open the V3-valve

In "RUN" mode, the HP buffer nitrogen level should be less than 75%.

 

Figure 2 Normal seetings of the cryocooling system.

LOM500: Piezo Table

For fine tuning of the LOM, three piezo motors are available:

  • height: 0 to 100 microns
  • pitch: - 500 to + 500 microrad
  • roll: -500 to + 500 microrad

Piezo Table Trouble Shooting

In case of strong intensity fluctuations (> 20%) with a frequency of some Hz (20s or 100s at the QBPM):< br\>

1) Restart the Piezo controller at the LOM (in the Optic Hutch): The PI-Piezo Controller is on the right (in beam direction) side of the LOM. 

  • Switch off 
  • Wait 5 seconds 
  • Switch on (wait until the LED changes from red to green). 

2) Initialize the Piezo controller:

  • Connect to haspp03lom by typing 'rdesktop -g 1500x1000 haspp03lom'. If it is not working on haspp03 you can log onto the Desy linux cluster (ssh username@pal, use desy username for login @pal) and issue the command from there.
  • Login to haspp03lom with username: ad2 password: MonoP03-500
  • Start "TWINCAT" and go to "Visualisation"-tab in the bottom left corner (if the programm is not running, start the Twincat PLC Control, login and run the programm)
  • Select "PIEZOTISCH_RS232"
  • Press the "Init" button (see Figure 3).

 Original

Figure 3 rdesktop connection to haspp03lom computer.

 

Figure 4 The Piezo Controller.









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