Techniczne aspekty LHC (Large Hadron Collider) Udział WFiIS AGH w uruchomieniu akceleratora Jan Kulka

Techniczne aspekty LHC (Large Hadron Collider) Udział WFiIS AGH w uruchomieniu akceleratora Jan Kulka 5-06-2009

- Zespół akceleratorów wokół LHC - Podstawowe systemy LHC oraz udział WFiIS AGH w uruchomieniu - Awarie - Perspektywy - Nadprzewodniki wysokotemperaturowe

5 B2 Dump 4 6 B1 Dump 3 7 2 SPS 8 1 LINAC 2 PSB CPS Top energy(gev) Circumference(m) LINAC2 0.12 30 PSB 1.4 157 CPS 26 628 = 4 PSB SPS 450 6911 = 11 x PS LHC 7000 26657 = 27/7xSPS

Injection mechanism: injection from pre-accelerators BOOSTER (1.4 GeV) PS (26 GeV) SPS (450 GeV) LHC BOOSTER (4 rings) 1 st batch 2 nd batch PS h=1 Two injections from BOOSTER to PS h=7 (6 buckets filled + 1 empty)

Injection mechanism: injection from pre-accelerators SPS h=84 h=21 h=7 PS h=1 BOOSTER Up to four injections from PS of 72 bunches 72 bunches 84 buckets 12x25 ns GAP to cover the 26 GeV rise time of the PS ejection 18 bunches kicker 21 buckets 1.4 GeV Two injections from BOOSTER to PS 6 bunches 7 buckets 1.4 GeV Quadruple splitting Triple splitting

The RF system: IR4 S34 ACS ACS ACS ACS Beam separation - Matching Section S45 recombination Quadrupoles ADT D3 dipoles D4Q5 Q6 Q7 B2 420 mm B1 194 mm Power Second Couple beam r Wave guide 4xFour-cavity cryo module 400 MHz, 16 MV/beam Nb on Cu cavities @4.5 K (=LEP2) Beam pipe diam.=300mm Tunnel

Two 300 kw klystrons with circulators and loads

RF cavities

10 th of September 10.09.2008

10 th of SeptemberBeam 1 First turn trajectory Betatron oscillation Each point is a BPM (Beam Position Measurement) ARC BPMs 49 mm aperture

10 th of September Beam 1 on TDI screen 1 st and 2 nd turns ALICE

10 th of September Beam 2 First turn trajectory Horizontal position (mm) Vertical position (mm)

Beam 2: Longitudinal Bunch Profile ~ 200 turns

IV.IV. 10 th of September Beam 2 closed orbit

10 th of September Beam 2 captured mountain range display Turn number Now RF ON Bunch length

10 th of September

Development of resistive zone in dipole bus bar splice R.Bailey, Aspen 2009 18

Bus bar splice R.Bailey, Aspen 2009 19

Working hypothesis Favored hypothesis for the S34 incident cause : Temperature increase due to excessive resistance (estimate ~ 200nΩ) Superconductor quenches and becomes resistive at high current Up to a certain current, the copper can take it (cooled by the He II) Beyond a certain current, run-away of the temperature, splice opens, electrical arc R.Bailey, Aspen 2009 20

Jarzmo stalowe dipola

Płyta kończąca dipola

Formowanie liry

Korpus ciśnieniowy zimnej masy

Wymiennik ciepła

Magnesy korekcyjne dipola (spool pieces)

Zamknięcie zimnej masy dipola dennicą

Dennica dipola i pozycjonowanie «Cold foot» Pozycjonowanie stóp

Mieszki kompensacyjne + linia N

Przekrój dipola LHC

Kompozytowa noga magnesu G10 Glass-fibre Reinforced Epoxy

Blokada dopływu ciepła Zasilanie ciekłym helem 4,5K (linia C ) Płyty aluminiowe klejone do nogi kompozytu G-10 Łączniki do łoża aluminiowego ekranu termicznego 50-75 K

Aluminiowe łoże magnesu wspornikiem ekranu termicznego

Izolacja aluminiowa zimnej masy

Wielowarstwowy koc izolacji termicznej (MLI)

Consequences 100m Considerable collateral damage over few hundred metres Insulating vacuum barrier every 2 cells in the arc Some moved Damage to superinsulation blankets Contamination (by soot and insulation blankets) of beam pipes R.Bailey, Aspen 2009 36 Large release of helium into the tunnel (6 of 15 tonnes)

Repair 100m Present strategy assumes treating all magnets Q19 to Q33 as shown 53 have to be brought to the surface (39 dipoles and 14 quads) Will be replaced with spare / refitted retested and reinstalled Estimate for magnets November 08 to March 09 Not forgetting cleaning the beam pipes Then have to finish interconnection, cool down, power test R.Bailey, Aspen 2009 37

Further measures Mitigate the consequences of any event similar to that in sector 34 by increasing the helium gas release capability All quadrupole cryostats have spare flanges Equip them with new full-flow release valves Gives Factor 8 in discharge cross section Can and will be done in situ at cold Addition of full-flow release valves on EVERY dipole cryostat (all 1232) Brings overall discharge cross section increase to Factor 40 Can only be done at warm Sector Present major activity foreseen in the different sectors Activity 34 Repair of magnets and beam pipes 56 Warmed up for repair of known non-conformity 12 Warmed up for exchange of dipole B16.R1 67 Warmed up for exchange of dipole B32.R6 R.Bailey, Aspen 2009 38 Others Kept cold

Restart in 2009 Installation of ALL protection systems would preclude a run in 2009 Install as much as possible in shadow of sector 34 repair Run with reduced risk in 2009 Complete installation of new protection systems for 2010 Restart in 2009 will be determined by Efficiency of logistics of magnets removal / installation Efficiency of magnet repair Efficiency of beam pipe repair / cleaning Efficiency of interconnection activities Time to cool down whichever sectors are warmed up Time to re-commission all power circuits Target is beam operation in second half of 2009 Lower energy (450GeV to 5TeV) Lower intensity (43 to 156 bunches per beam) Push performance in 2010 R.Bailey, Aspen 2009 39

Prospects 2009 Repair of Sector 34 Hardware commissioning to 5TeV Machine checkout Beam commissioning 5TeV Low intensity operation No beam Beam 2010 Complete installation of protection systems Train towards 7TeV Machine checkout Beam Setup Increase number of bunches Increase intensity No beam Beam R.Bailey, Aspen 2009 40

Skład osobowy pracowników AGH pracujących przy uruchomieniu LHC w okresie 2005-2009 Bednarek Ludwin Prochal Setkowicz Drózd Filipek Gorzawski Nowak Nowak Seweryn Skała Skoczeń Wojanek MEL Mateusz Jaromir Bogusław Józef QP Adam Wiesław Arkadiusz Edward Elżbieta Grzegorz Aleksander Andrzej Piotr QRL Bolewski Andrzej Ciechanowski Marek Donizak Jędrzej Dubert Paweł Fluder Czesław Gaj Wawrzyniec Jodłowski Paweł Klisch Michał Macuda Paweł Malinowski Paweł Palica Jan Skotnicki Ryszard Sosin Mateusz Wróbel Bartłomiej Zwaliński Łukasz Lis Krzysztof Wolak Tomasz Macuda Szkutnik Baran Dubert Pomocka Urbaniec Wiencek Kulka TS TS/CV Małgorzata Jacek Krzysztof Anna Marek Bartłomiej Mateusz CRI Jan

Equivalent thermal conductivity 2000 of He II Y(T) ± 5% 1500 1000 2.4 ( &) = & ( ) K T,q q Y T dt dx = q& Y(T) q & in W / cm T in K X in cm 3.4 2 Helium II 500 OFHC copper Tλ 0 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 T [K]

Phase diagram of Helium 10000 SOLID 1000 P [kpa] 100 HeII Pressurized He II λ line HeI CRITICAL POINT GAS 10 Saturated He II 1 1 10 T [K]

Magnes dipolowy, jeden z 1232 w LHC, temp. pracy 1,9K 7TeV 8.33T 11850A 7MJ

Linear heat exchanger

Elementy sytemu kriogenicznego

Linia dystrybucyjna ciekłego helu o długości 3,3km

Przepływy helowe w komórce kriogenicznej LHC LHC Standard Cell (106.9 m) F Thermal shield B D C HX100 Cryogenic Distribution Line HX100 TCV2 SRV CFV TCV1' TCV1 TCV2 TCV2 SRV SRV TCV1' TCV1 TCV2 Beam screens Support posts MB MQ MB MB MB MQ MB MB MB MQ X Y L E Supports and thermal shield LHC magnet cryostat

indukcja B µ 0 Jbd = y a + b B B x y µ 0J ( a b) = a + b µ 0J ( a b) = a + b y x

Kryterium selekcji Liczba Nadprzewodnik 10,000 T c 10 K.and. B c2 10 T 100 J c 1 GA/m 2 @ B > 5 T 10 Magnet-grade superconductor 1

Niob-Tytan Critical current density vs field measured on NbTi multiflamentray wire at 4.22 and 2.17 K Jc(A/mm 2 ) 11000 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 LHe HeII 0 1 2 3 4 5 6 7 8 9 10 11 12 B tot (T) Critical surface of NbTi (from Wilson textbook) Critical current of best Cu/NbTi with typical 3 T field shift at superfluid helium (INFN-LASA lab, february 2000)

Grzejnik quenchowy

Ekran wiązki

Energy stored in LHC magnets Energy stored in twin dipole magnet: E stored := 2 2 2 B dipole length rdipole π µ 0 Approximation: energy is proportional to volume inside magnet aperture and to the square of the magnet field E dipole = 0.5 L dipole I 2 dipole Energy stored in one dipole is 7.6 MJoule For all 1232 dipoles in the LHC: 9.4 GJ

Energy stored in the beams 25 ns Beam energy: Proton Energy Number of Bunches Number of protons per bunch Proton Energy: 7 TeV In order to achieve very high luminosity: Number of bunches per beam: 2808 Number of protons per bunch: 1.05 10 11 Energy per beam: 346 MJoule 56

Schematics of the QPS in the main dipoles of a sector Cold diode Quench Detectors V1-V2 0 R Power Converter L1 (SC Magnet) Switch L2 (SC Magnet) L154 (SC Magnet) Quench Heaters R (Energy Extraction)

If not fast and safe During magnet test campaign, the 7 MJ stored in one magnet were released into one spot of the coil (inter-turn short) P. Pugnat

Schemat zrzucania wiązki Beam 1 Q5L Fast kicker magnet Q4L Septum magnet deflecting the extracted beam H-V kicker for painting the beam about 700 m Beam Dump Block Q4R about 500 m Q5R Beam 2 59

DFBAO in Sector 7-8

HTS in the LHC machine Powering of the LHC magnets About 3 MA of rated current for 1800 circuits 3286 current leads Quantity Current rating (A) 64 13000 298 6000 820 600 2104 60-120 HTS Superconducting Magnets Summer 2006 Tom Taylor 61

L. Evans R. Saban R. Bailey K-H. Mess K. Dahlerup-Petersen T. Taylor Podziękowania: