3/1/05 Status of the SHBD for the NUMI OPERA exposure D. Autiero IPN Lyon

1. 3/1/05 • Status of the SHBD for the NUMI OPERA exposure • D. Autiero IPN Lyon • Reminder about the proposed setup for the SHBD • Status of the sub-detectors • Details on the operation of the silicon telescope in October 2004

2. Hybrid sophysticated detector: • The high intensity of the NUMI beam at the near detector location allows to work with a small target mass and compact and sophisticated detectors (not possible with CNGS), made with all recycled components It is possible to build a precise detector around a single brick • It is a good occasion to perform a precise measurement of all what is produced in the neutrino interaction in the brick and to check also the production of backward particles which is relevant in OPERA for the BF analysis. We are interested in particular in the HE run • These results are also useful for the neutrino community for the investigation of nuclear effects, bricks can be made in Pb, Fe • This is not a new experiment (in competition with MINERVA) but just a test-beam performed with a small setup with the goal of collecting a few hundreds nm CC well measured.

3. Precise tracking in the forward and backward direction • Forward calorimetry • Detector for backward neutrons Veto Detector for Backward Neutrals (scintillator bars) Minos near Detector (HCAL Muon ID) ECC ECAL Silicon tracker planes 1.5 m Max

4. The detector is made with existing/recycled components We can afford a sophisticated detector for one brick, given its small size. This is possible due to the high neutrino flux. The detector can fit in a space of 1.5 m longitudinal, < 1 m transverse which, can be available in between Minerva and Minos due to the MINOS ND coils (The magnetic field map should be checked) . The idea is to change the brick exposed a few times per day (depending on the max number of interactions we want to accept per brick (HE run: 27 interactions per day). The neutron detector will be made of scintillator strips ‘we can recycle some of the TT building waste) with WLS fibers readout and M64 photomultipliers + standard opera TT electronics. The layers of strips will be crossed in X and Y.

5. For the neutron detector one possibility is to have just in the side close to the brick a thin foil of lead to be used as preshower in order to distinguish photons from neutrons. This could be put just at the beginning or after a few layers (2 layers) of scintillator in order to allow to detect some soft particles which would die in the lead (to be optimized with the ongoing simulation) Pb, in this case put at the beginning Backward Neutron detector Eff=60% g ECC n p Some passive material could also be introduced among the scintillator layers for a better containement, probably we will have to put an absorber in between the veto and neutron detector in order not to reject interesting events 50 planes of 8 strips 20 cm 400 channels

6. The Si tracker can be recycled from a CMS prototype The ECAL can be recycled from NOMAD lead-glass prototypes The trigger will be based on the ECAL + VETO In order to isolate the interactions really happening in the brick instead than in the ECAL or the neutron detector one has to look at the hit/tracks pattern in the Si tracker planes (check before the brick extraction) The connection with the events measured with the MINOS DAQ (as for the SFT detector) will be done on the basis of the time-stamp (GPS signal)

8. Status (January 2005): • 8 Multianode PM Hamamatsu M64 have been bought for the construction of the backward neutron detector. The corresponding readout electronics is available from the OPERA Target tracker. The construction of the detector recycling strips and fibers from the OPERA TT has to be started. • The 9 lead-glass blocks can be recuperated from the old NOMAD electromagnetic calorimeter in order to assemble the forward Ecal. • Silicon telescope operating in October 2003 for the OPERA measurement of large angle muon scattering in lead • It was built from material recuperated from CMS • The telescope has succesfully collected more than 70 millions of events during the run at the SPS X5 test-beam in October 2004 • The structure of the telescope is already the one that would be needed for the SHBD (3 X + 3 Y views before and after the brick, 12 planes in total) • The mechanical structure hosting the silicon detectors will have to be redone since it has no space in the middle to host a brick, all the rest can be kept unchanged • The CMS people who have been collaborating for the OPERA test suggest for the FNAL run to involve their US collaborators, this will easy a lot the installation and operation of the detector. First direct discussions will take place at CERN at the beginning of February

9. Recuperated from CMS TOB (Outern Barrel): 500 micron tickness 512 strips with 180 microns pitch Dimensions 9.6 cm x (9.6 x2) Front-end with Optoelectronic readout ADC 8 bits Fast electronics (LHC) working on 25ns cycles Silicon detectors: Resolution: Single strip 180/sqrt(12)=50 microns Charge centroid: about 25-30 microns 20 mrad -> 1.8 mm displacement among two consecutive planes of the same view

10. Telescope assembly frame (recuperated from an old MSG telescope): Hosting 12 planes: 6 planes (alternatively X and Y) before + 6 after the target The planes are orthogonal, overlapping for a surface 9.6x9.6 cm2 and rotated by 45 degrees with respect to the vertical Planes (X or Y) pitch 91 mm Redone: Silicon detectors supports and cooling system Target position

11. Telescope new readout card centralising controls, clock, Vbias Optoelectronic cards

12. Water cooling circulation in the support frames

13. T2 Magnet MWDC2 The telescope in its insulated and ligth tight box Water Cooling Nytrogen flow T=19 C constantly monitored R.H.=30% T3