MDI Status and Plans Lau Gatignon Beam Physics

MDI Status and Plans Lau Gatignon, Beam Physics Meeting A summary, not an exhaustive list

Outline Present status Longer L* option (QD 0 in tunnel) Background studies QD 0 prototype tests and measurements Anti-solenoid QD 0 Stabilisation studies QD 0 Pre-alignment follow-up Post-collision line Cavern layout and push-pull MDI Status and Plans 2 L. Gatignon, 22 -02 -2012

Why is QD 0 inside detector (in CDR)? L* = 3. 5 m gives potentially largest luminosity This is the most challenging in terms of QD 0 strength, stabilization and integration difficulties If you can make this solution plausible, all other solutions should a fortiori be possible L* = 8 m seemed to be ruled out because of unrealistic prealignment constraints (2 m) Therefore we concentrated on the L*=3. 5 m solution for the Conceptual Design Report. Note: 4 QD 0 magnets are needed MDI Status and Plans 3 L. Gatignon, 22 -02 -2012

Plus othe MACHINE DETECTOR INTERFACE rs …… …. . Anti-solenoid IP Feedback Beamcal+ Lumical Vacuum s le o p u Support tubes L. Gatignon, 22 -02 -2012 0 QD dr a u q +Stabilization + prealignment 4

L. Gatignon, 22 -02 -2012 MDI Status and Plans 5

L. Gatignon, 22 -02 -2012 MDI Status and Plans 6

The QD 0 support tube and QF 1 are mounted on a pre-isolator Concrete mass of ~ 80 tons mounted on calibrated springs. Eigenfrequency ~ 1 Hz. Designed to reduce vibrations by a factor of ~ 30. See F. Duarte Ramos talk L. Gatignon, 22 -02 -2012 MDI Status and Plans 7

Why QD 0 in the tunnel? The double QD 0 support tube plus anti-solenoid eats up a significant part of the forward acceptance in the case of shorter L*. The shorter L* is different for CLIC_Si. D and CLIC_ILD, leading to severe complications for either MDI or BDS. End-coils allow to shorten the detector length to about 13 (= ± 6. 5) m, therefore L* ~ 6. 5 m can be considered instead of 8 m. For L* = 6 m the pre-alignment tolerance becomes 8 m, (almost) ok. Also the radiation environment is easier for stabilisation and alignment Stabilization becomes easier, as well as the anti-solenoid and many integration issues. (Therefore more realistic to reach Lnom? ) Only 2 QD 0 magnets are needed (same L* by definition) MDI Status and Plans 8 L. Gatignon, 22 -02 -2012

So the questions are How much luminosity does one loose (on paper)? How much acceptance can one gain (on paper)? How serious is the luminosity loss with respect to the difficulties to keep it stable inside the detector environment, i. e. are there effective luminosity losses due to such issues for the short L* ? What is the net balance between luminosity and acceptance in terms of the physics reach? These questions deserve proper answers ! MDI Status and Plans 9 L. Gatignon, 22 -02 -2012

What are the steps What is the potential gain in acceptance, i. e. which systems have to be maintained in the detector region and can they be moved How much luminosity do we loose, what are the QD 0 and QF 1 parameters: gradient, length, aperture, cohabitation with spent beam Once the new detector acceptance has been defined, the physics can decide what luminosity loss can be tolerated. MDI Status and Plans 10 MDI BDS LCD L. Gatignon, 22 -02 -2012

More in practical terms for Step 1 (MDI) How large must the anti-solenoid be, keeping in mind that it must cover the spent beam as well. Note that QD 0 is no longer there to shield the main solenoid field in this region. Must the IP feedback remain inside the detector, and if so, where? Is there a better location for Beamcal and Lumical The vacuum system is probably simplified, but do we need valves inside the detector volume and what is their position and size. Does the vacuum pressure requirement change with the longer lever arm? MDI Status and Plans 11 L. Gatignon, 22 -02 -2012

More about step 1 Do we still need a pre-isolator and, if so, should it be modified? Are there impacts on the backgrounds, e. g. does the argument for a thick vacuum tube remain valid? Are the arguments for radiation shielding still valid, do we still need PAC-rings? How do we have to modify the integration studies for the pre-alignment? MDI Status and Plans 12 L. Gatignon, 22 -02 -2012

Detector Integration Radiation Lever arm Space Forces MDI Status and Plans 13 L. Gatignon, 22 -02 -2012

A starting point (for discussion)? MDI Status and Plans 14 L. Gatignon, 22 -02 -2012

MDI Status and Plans 15 L. Gatignon, 22 -02 -2012

Further considerations on L* The LCD work depends on the conclusions for the acceptance in the L* ~ 6 m solution The BDS work is significant amount of work, it is important and will take too long to have us waiting for this On the other hand, in my view there is nothing that prevents us from starting the MDI bit! Many of the ongoing studies remain useful for both the short and longer L* solutions. MDI Status and Plans 16 L. Gatignon, 22 -02 -2012

Backgrounds The main backgrounds come from: The IP itself: (in)coherent pairs, tridents, → hadrons, etc Studied by Beam Physics and by LCD groups Muons from the BDS collimators Electron tails at collimators studied by Daniel and Helmut, Muon tracking by Lawrence Deacon Neutrons and photons backscattered from dumps and absorbers So far by PCLD WG, from now on by MDI: Lawrence MDI Status and Plans 17 L. Gatignon, 22 -02 -2012

e. g. Muon backgrounds • BDSIM simulations • Based on tail estimates, muon spoilers needed to reach well below 1 muon / BX • Recent developments in electron beam tail estimates, now very much smaller than estimated before MDI Status and Plans 18 L. Gatignon, 22 -02 -2012

e. g. Background rates from IP Courtesy Barbara Dalena Beam-Beam products per BX [*] Beams parameters and Luminosity Total Luminosity [1034 cm-2 s-1] Peak Luminosity [1034 cm-2 s-1] 2. 0 fr [Hz] 50 Nb t 5. 9 312 [ns] N 0. 5 0. 372 e+10 z [ m] 44 x / y [nm]/[nm] 660/20 *x / *y [nm]/[nm] 45/1 MDI Status and Plans 19 ΔE/EBS 29 % n 2. 1 (x N) Ncoherent 66 e+7 Ntrident 67 e+5 Nincoh_pairs 330 e+3 Nincoh_muons 12. 50 NHadrons 3. 2 Nrad_bhabhas 110 e+3 L. Gatignon, 22 -02 -2012

QD 0 prototype measurements The QD 0 magnet has a very challenging nominal gradient of 575 T/m and a length of 2. 73 m We chose a hybrid technology, combining PM and coils The magnet group (M. Modena et al) have built a 10 cm long prototype, which is at present under test: field and quality measurements In the plans: rad-hardness, external field impact, …. MDI Status and Plans 20 L. Gatignon, 22 -02 -2012

Some field measurements: For Nd. Fe. Br permanent magnet material A very promising start indeed! Basic technology choice seems validated. MDI Status and Plans 21 L. Gatignon, 22 -02 -2012

Anti-solenoid design The main purpose is to protect the QD 0 permanent magnet material against the external field of the main solenoid (4 or 5 T) of the detector and to cancel its impact on the beam and in particular on the luminosity. Important to define practical criteria for efficient optimisation MDI Status and Plans 22 L. Gatignon, 22 -02 -2012

Some results for Antisolenoid Courtesy: Antonio Bartalesi • Good axial field cancellation • But significant reduction of luminosity due to radial field components at the exit of QD 0 magnet • Very significant forces act on the anti-solenoid • Need quite a bit of space! MDI Status and Plans 23 L. Gatignon, 22 -02 -2012

QD 0 stabilisation Stabilisation to 0. 13 nm has been demonstrated in the lab (LAPP, but also 0. 2 nm at CERN) However, the detector environment is more challenging than the lab Also one has to cope with stringent space and integration constraints Tests are ongoing in the stabilisation working group, at LAPP and at CERN MDI Status and Plans 24 L. Gatignon, 22 -02 -2012

Stabilisation conditions Ground motion much smaller in tunnel than in the experiment (CMS) Decide for QD 0 mounted from tunnel on passive pre-isolator Add active stabilisation system with piezo actuators MDI Status and Plans 25 L. Gatignon, 22 -02 -2012

Pre-isolator in tunnel F. Duarte Ramos et al MDI Status and Plans 26 L. Gatignon, 22 -02 -2012

Active stabilisation Courtesy: A. Jeremie MDI Status and Plans 27 L. Gatignon, 22 -02 -2012

Active stabilisation (2) MDI Status and Plans 28 L. Gatignon, 22 -02 -2012

Overall luminosity simulation J. Snuverink, D. Schulte MDI Status and Plans 29 L. Gatignon, 22 -02 -2012

QD 0 Pre-alignment QD 0 pre-alignment is critical: 10 micron in a place where there is no direct visibility through the detector A collaboration has been established between the Survey team (H. Mainaud) and a NIKHEF group It relies on a RASNIK-like approach, combined with WPS and stretched wires MDI Status and Plans 30 L. Gatignon, 22 -02 -2012

The principle MDI Status and Plans 31 L. Gatignon, 22 -02 -2012

Test set-up at NIKHEF MDI Status and Plans 32 L. Gatignon, 22 -02 -2012

The Post-Collision Line Courtesy: Edda Gschwendtner MDI Status and Plans 33 L. Gatignon, 22 -02 -2012

E. g. : Origin of backscattered photons Courtesy Lawrence Deacon MDI Status and Plans 34 L. Gatignon, 22 -02 -2012

Other PCL studies Courtesy: A. Apyan Luminosity measurement from muon pairs produced in the final beam dump Impact of radiation on lifetime of magnets Stray field of PCL magnets on the BDS line? etcetera MDI Status and Plans 35 L. Gatignon, 22 -02 -2012

Cavern layout and push-pull The cavern layout must be democratic between the two experiments The cavern layout must be compatible with stabilisation and pre-alignment boundary conditions A proposal has been made by the PH-LCD group in close collaboration with civil engineering. The ARUP company has been mandated to study this layout for CLIC as well as push-pull platforms (rather for ILC). This is being followed closely by MDI and CE MDI Status and Plans 36 L. Gatignon, 22 -02 -2012

MDI Status and Plans 37 L. Gatignon, 22 -02 -2012

MDI Status and Plans 38 L. Gatignon, 22 -02 -2012

MDI Status and Plans 39 L. Gatignon, 22 -02 -2012

MDI Status and Plans 40 L. Gatignon, 22 -02 -2012

Conclusion Lots of topics Lots of interesting work Lots of this involves beam physics! Thanks for your attention! and apologies to those I did not mention MDI Status and Plans 41 L. Gatignon, 22 -02 -2012