Beamstrahlung on the Septum Blade Karsten Ber 01

Beamstrahlung on the Septum Blade Karsten Büßer 01. 04. 2003 ECFA/DESY Workshop Amsterdam

The Extraction Line Problem Beamstrahlung Incoming Beam Outgoing Beam 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 2

Beamstrahlung Distributions N. Walker (Prague): Realistic Beam Effect of 10 σ offset Expectation: Power on septum blade can reach several k. W 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 3

Questions Formation of a working group to revisit the design of the extraction line. First Meeting on December 3 rd 2002 identified the following questions: • Septum magnet design • Failure modes • What power can the thin blade cope with ? • Reliability of electro-static separators • IR is a highly charged environment • Power loss from the charged particle extraction ? • Is a (small or large) crossing angle a solution ? • 800 Ge. V upgrade How much energy is really deposited in the septum blade ? 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 4

Disclaimer All I am going to present is right out of the press and is therefore to be considered VERY PRELIMINARY 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 5

Simulating the Extraction Line Part of the extraction line included in BRAHMS: Shadow: • Distance from IP: 45 m • 2 m long • 5 mm thick • 7 mm vertical distance from nominal beam (~156 µrad) • Copper Septum Blade: • Distance from IP: 47 m • 16 m long • 5 mm thick • ~7 mm vertical distance from nominal beam • Copper 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 6

Realistic Beams Simulation of the complete machine done by Glen White. Using: • LINAC: PLACET (D. Schulte) • BDS: MERLIN (N. Walker) • Beam-beam: GUINEA-PIG (D. Schulte) Takes into account: • Simulation of feedback loop • Orbit injection errors into LINAC • Wakefield effects in LINAC • Vibration of quads in BDS • Energy spread of e- due to undulator • Resolutions of BPMs • Jitter on kicker signals Beams and backgrounds are available through database at hepwww. ph. qmul. ac. uk/lcdata 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 7

Nominal Beam • Total average Beamstrahlung power: ~360 k. W • Integrated power in septum blade area: ~60 W 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 8

Realistic Beam • Feedback system brings beams into stable collisions after ~100 BX • Total average Beamstrahlung power: ~500 k. W (TDR 360 k. W !) • Integrated power in septum blade area: ~35 k. W 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 9

Colliding with the Septum 5 Ge. V Photon 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 10

Nominal Beam • Shadow: Average deposited power: ~40 W • Septum blade: Average deposited power: ~0. 3 W 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 11

Realistic Beam • Shadow: Average deposited power: ~15 k. W • Septum blade: Average deposited power: ~80 W 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 12

Conclusion • Under realistic beam conditions, 30 -40 k. W of Beamstrahlung are emitted under vertical angles larger than 0. 155 mrad. • Roughly half of the emitted energy is deposited in the septum shadow. • Septum blade receives on average 80 W. → Information from Efremov: 15 k. W has to be cooled away from septum blade due to normal operation. → Septum will probably undergo no mechanical damage. → 40 k. W of Beamstrahlung will irradiate the septum environment. To be done • Check backgrounds for the detector. → Backscattering → Pairs, neutrons with realistic beam • Check charged particle extraction losses. 01. 04. 2003 Karsten Büßer - Beamstrahlung on the Septum Blade ECFA/DESY Workshop Amsterdam 13