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Datasheet QM52 (v1.3) [Type text] 2016.11.20 Datasheet QMP52 crystal Crystal assembly description QMP52 is a crystal assembly (Figure 1) designed for investigations in the frame of Crystal collimation experiment (UA9). The crystal assembly consists of metal bending device and silicon crystal bent inside of bending device with means of quasi mosaic effect. The main purpose of crystal assembly is to deflect charged particles hitting outer part of crystal by means of channeling effect. It has been designed for the installation into the high precision goniometer for the crystal collimation research of high energy halo particles circulating in the LHC. The design of bending device has been developed in PNPI (Gatchina) to be assembled without any single screw in order to effectively resist against thermal shocks for long term stability. Crystal parameters y Dimensions: z Full assembly Height (y) mm Width (x) mm Length (z) mm Total weight g Crystal Height (y) mm Width (x) mm Width of outer part mm Length (z) / along the beam mm Crystal characteristics: Planar channeling plane Miscut angle for channeling Defection angle Efficiency of deflection (protons 400GeV/c) urad rad 40 ± 0.05 29.6 ± 0.1 25 ± 0.1 95.75 ± 0.01 x 27 ± 0.02 30 ± 0.02 6.5 ± 0.1 4 ± 0.02 (111) 25 ± 10 55 ± 3 69 ± 3 Date of final assembly: 2015.06.05 Figure 1. QM crystal of LHC-type Bending device The bending device consists of five (5) metal parts bending one silicone crystal. The four metal parts made of Titanium alloy Grade 5, one part made of Beryllium bronze (see the list of materials below). 1 Datasheet QM52 (v1.3) [Type text] 2016.11.20 All the titanium parts have passed through the standard thermal annealing process at 700°C in order to release possible mechanical internal tensions induced by manufacturing of raw material. This operation is obligatory for components critical to long term stability of shape. The assembly doesn’t contain screws or adjustable elements, it keeps the bending of crystal by means of internal spring and capable to be heated up to 300°C. All the parts have been manufactured with the following treatments: milling, grinding, deep optical polishing. One part after polishing has been coated by high reflective nickel-molybdenum alloy in order to provide flat reflective surface which is used for optical alignment of crystal mounted into goniometer. The crystal with bending device has been assembled on June 5th 2015 following with measurements of bending angle with H8 test beam in CERN. List of Materials ● ● ● ● Spring - Beryllium bronze CuBe2 (known also as Alloy 25, C 17200); Bending device (4 parts) - Titanium alloy Grade 5 (known also as Ti-6Al-4V), it is a chemical composition of Titanium with 6% of Aluminum, 4% of Vanadium, 0.25% (maximum) of Iron, 0.2% (maximum) of Oxygen; Crystal – monocrystalline silicon; Round mirrors - Nickel-Molybdenum non-magnetic alloy sputtered on titanium optical polished surface. The mirror has a round shape of diameter 11 mm and thickness ~2.7 𝜇m. Heating test Crystal assembly was treated with the heating test at vacuum lab in b.SMA18 performing the thermal profile with the following characteristics: heating under vacuum < 10-5 bar at temperature 250°C during 24 hours with ramp up/down 50°/h. The heating test of QMP52 was performed 2 times with characterization by means of H8 beam before and after heating: - 8th June 2015 in the vacuum lab of b. SMA18; - 4th July 2016 in the vacuum lab of b. SMA18. Crystal characteristics While manufacturing during February-May 2015 crystal assembly was passed through multistage process of grinding and deep polishing of all the surfaces with the control of orientation of working crystal planes (111) with respect to the crystal face. Miscut angle of crystal represents a misalignment between optical surface of working face and (111) crystal planes. At the final production stage the miscut angle was characterized by means of X-rays diffractometer and resulted to be better than 50 rad with the following deep polishing. The miscut angle of assembled crystal device was measured with X-ray setup in 2016 with result 25 ± 10 rad. During manufacturing and preliminary assembly crystal bending angle was characterized at PNPI by indirect optical methods based on measurement of primary bending curvature by means of profilometer based on while-light interferometry principle and custom developed equipment for characterization of optical surfaces 2 Datasheet QM52 (v1.3) [Type text] 2016.11.20 shape known based on deflectometry. After final assembly the crystal bending features were characterized by means of direct method on H8 test beam of protons with the energy 400 GeV/c and later with pions 180 GeV/c. The measurements were performed before and after heating without additional optical indirect characterization after beam tests. The deflection angle of crystal by means of channeling effect is described as a difference between incoming and outcoming trajectories of charged particles hitting crystal in the oriented conditions. This kind of deflection is characterized also by channeling efficiency which is the fraction of deflected particles with respect to flux hitting crystal in the selected geometrical region on crystal. The torsion of crystal is the changing of crystal plane orientation vs. vertical impact position. The following Table 1 represents direct measurements of deflection angle and channeling efficiency performed for crystal QMP52 with test beams. The respective results of characterization are also show on Figure 2and Figure 3. Table 1. Results of crystal characterization # Conditions Date 1 before heating 2 2015.06.06 2 after heating 2 2015.06.13 3 before heating 3 2016.07.01 4 after heating 3 2016.07.05 5 after heating 3 2016.09.16 Beam Deflection angle 400 GeV proton beam 400 GeV proton beam 180GeV pion beam 180GeV pion beam 180GeV pion beam 3 rad 54.3 ± 2.5 Efficiency (±5 rad beam divergence) % 67.7 ± 3.5 Torsion (±2mm in vertical) rad/mm <1 55.0 ± 2 69.7 ± 3 <1 57.8 ± 3 66.3 ± 4 - 55.4 ± 2 64.8 ± 4 - 54.5 ± 3 65.8 ± 4 - Datasheet QM52 (v1.3) [Type text] 2016.11.20 70 Deflection angle, rad Protons 400 GeV/c Pions 180 GeV/c June 2015 65 July 2016 Sept. 2016 60 55 50 45 bakeout 2 bake-out 3 40 1 2 3 4 5 Test # Figure 2. Measurements of crystal deflection angle 85 Protons 400 GeV/c Deflection angle, rad 80 Pions 180 GeV/c June 2015 July 2016 Sept. 2016 75 70 65 60 55 bakeout 2 bake-out 3 50 1 2 3 4 5 Test # Figure 3. Measurements of crystal efficiency deflection 4