S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.091

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

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.092

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

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.093

0 5 10 15-5-10-15-20-25

Q15 Q16 Q17

m

sm

0

5

10

-5

-10

2.525

10-5

collimation tails on the targetby CX and CY

collimaton of anglesby vacuum tube

vacuum conewithout interactions with ions

2.525

io beam

io beam

ion beamwith tails

sources of secnday particles

Y (vertical)

X horisontal

ion beamwith tails

vacuum tubeino quadrpolesD=160mm

measurements by CBMbetween 2.5 and 25 degrees

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

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.094

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.)

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.095

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 1011 ions per second.

We stay with a vacuum pipe

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.096

Conceptual design of the vacuum chamber and the beampipe

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.097

Beryllium beampipe features

Be: A=9, Z=4 =1.85 g/cm3 E=300 GPa =300-500 MPa =1-3% X0=35.28 cm

> 1022 n/cm2

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?

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.098

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.099

New Info for filling the magnet

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.0910

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

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.0911

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 cm2

P-pitch, l – strip length, Nh –number of real hits, Nf – number of fakes, – “strip fired” probability, S – area seen by a strip

2

2

2

2

2

p

tg

S

N

lp

SNN

lp

SN

tglS

f

hf

h

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.0912

Remarks about composition of the STS modules

Station 1 (min strip 0.7 cm), central part. =3.5%, Nf/cm2=12, Nh/cm2=10

Station 4 (strip 12 cm), peripheral part. =1.8%, Nf/cm2=3.2, Nh/cm2=0.3

Station 1 (strip 4 cm), peripheral part. =2%, Nf/cm2=4, Nh/cm2=1

Station 1 (min strip 1.4 cm), central part. =7%, Nf/cm2=48, Nh/cm2=10

This fake density may be essential not only for tracking time, but even more for hypothetical tracker working with gaps

S. Belogurov, ITEP, Moscow CBM Collaboration meeting, Split, 06.10.0913

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.