1. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 1 CBM beam pipe and integration inside the Magnet Status report Sergey Belogurov, ITEP, Moscow Outline - Properties of the beam at SIS 100. Data from the FAIR team - Conceptual design of the vacuum chamber and the 1-st section of the beampipe - Beryllium beampipe features - New Info for filling the magnet with the STS service equipment - Remarks about composition of the STS modules

2. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 2 Properties of the beam at SIS 100. Data from the FAIR team S. Ratschow The beam half diameter at the CBM Target is 2.44mm (horizontal) 1.5mm (vertical). 2*beam width ~90-95% of particles Effects of the last q diameter - filling up the phase space (intensity) - size of the spot at the target (1/d) Tail treatment – collimators (M. Kats, ITEP) Last q-lens to HADES – 3m to CBM - 15 m

3. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 3 Properties of the beam at SIS 100. Data from the FAIR team Taken from analysis of collimator system for SIS300 by Dr. M. Kats, ITEP

4. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 4 Properties of the beam at SIS 100. Data from the FAIR team Issues for CBM: Radiation environment when the beam is focused at HADES (Beam size at the CBM magnet is ~ 1 m). Beam dump between the experiments? Size of the beam at PSD position during normal operation (~12 cm at 10 m, 17 cm at 15 m) We need to know the minimum energy we may use with the max. field of CBM magnet, both for SIS 100 and SIS300 (deflection of the beam in the field of our magnet.)

5. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 5 Conceptual design of the vacuum chamber and the beampipe Following Karelia meeting Iouri and Anna have checked the option of He bag as a beam pipe (inspired by NA61). It is NOT acceptable due to mimic of charm not far from the target and huge production of  -electrons in the STS region by 10 11 ions per second. We stay with a vacuum pipe

6. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 6 Conceptual design of the vacuum chamber and the beampipe

7. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 7 Beryllium beampipe features Be: A=9, Z=4  =1.85 g/cm3 E=300 GPa  =300-500 MPa  =1-3% X 0 =35.28 cm  > 10 22 n/cm 2 At the next slide: design coordinated with Beryllium institute and accepted for mechanical simulations and optimization The main question: are we sure that vacuum window won’t move back to 25 cm from target?

8. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 8

9. 9 New Info for filling the magnet

10. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 10 New Info for filling the magnet Evgeny Matyushevsky and E. Litvinenko, JINR the magnet with the screens (RICH mode of CBM) - field map: /d/cbm01/litvinen/data/2009/FieldMaps/FieldSC_16x13.root geometry: /u/litvinen/cbm/JUN09/geometry/magnet_sc_16x13.geo the magnet without the screens (MUON mode of CBM) - field map: /d/cbm01/litvinen/data/2009/FieldMaps/FieldSCmuon_16x13.root geometry: /u/litvinen/cbm/JUN09/geometry/magnet_scmuon_16x13.geo We should use these files and remove from cbm-root release (or at leas mark as obsolete) field active and muon magnets! Space for inductive voltage converters

11. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 11 Remarks about composition of the STS modules The algorithm for the sensor size selection require constant “strip fired” probability which leads to constant number of fakes per cm 2 P-pitch, l – strip length, N h –number of real hits, N f – number of fakes,  – “strip fired” probability, S – area seen by a strip

12. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 12 Remarks about composition of the STS modules Station 1 (min strip 0.7 cm), central part.  =3.5%, N f /cm 2 =12, N h /cm 2 =10 Station 4 (strip 12 cm), peripheral part.  =1.8%, N f /cm 2 =3.2, N h /cm 2 =0.3 Station 1 (strip 4 cm), peripheral part.  =2%, N f /cm 2 =4, N h /cm 2 =1 Station 1 (min strip 1.4 cm), central part.  =7%, N f /cm 2 =48, N h /cm 2 =10 This fake density may be essential not only for tracking time, but even more for hypothetical tracker working with gaps

13. S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.09 13 Conclusions Current understanding of the SIS 100 beam does not assume really small beam spot size at CBM target. For single layer target it could be still OK. Anyway we’ll negotiate with the SIS team and optimize the parameters. 0.5 mm thick Be beampipe seems feasible and acceptable Current segmentation algorithm produces huge amount of fake hits especially in peripheral zones of STS stations. We should analyze possibility to increase number of channels.