Hi Lum Experiment Univ of Arizona Univ of

Hi. Lum Experiment Univ. of Arizona; Univ. of Dresden; JINR Dubna; IEP Košice; Univ. of Mainz; LPI Moscow; MPI Munich; BINP Novosibirsk; IHEP Protvino; TRIUMF Vancouver; Univ. of Wuppertal; Proposal: 2005 First Beam run: 2007 NIM papers: NIM A 669 (2012) 47, Second paper in progress Goal: establish limitations on the operation of the endcap calorimeters (FCAL, EMEC, HEC) at highest LHC luminosities 28 December 2021 Hilum Status February 2016 1

Analysis of EMEC HV currents EMEC (LAr gap of 2 mm) Preliminary Filter: Plateau flatness, 2 , correlation factor 28 December 2021 Hilum Status February 2016 2

Analysis of EMEC HV currents EMEC (LAr gap of 2 mm) Preliminary I 0. 75 EMEC: for I>Ic: I=Ic · (I/Ic)0. 75 expected with Ic ~ 1. 5 x 108 p/s; 28 December 2021 Hilum Status February 2016 3

Analysis of EMEC HV currents Preliminary EMEC (LAr gap of 2 mm) EMEC: for I>Ic: I=Ic · (I/Ic)0. 75 expected with Ic ~ 1. 5 x 108 p/s; 28 December 2021 Hilum Status February 2016 4

Analysis of EMEC HV currents: O. Novgorodova EMEC (LAr gap of 2 mm) Preliminary: average of both methods Ic = 1. 30 ± 0. 06 (stat. ) ± 0. 30 (sys. ) x 108 p/s p = 0. 728 ± 0. 004 (stat. ) ± 0. 005 (sys. ) But amplitude method is more appropriate Amplitude method: Ic = 1. 64 ± 0. 05 (stat. ) ± …. p = 0. 724 ± 0. 004 (stat. ) ± … 28 December 2021 Hilum Status February 2016 5

Analysis of EMEC Signal: A. Savin EMEC (LAr gap of 2 mm) Tint=20 ms; Colors indicate different beam impact positions; black corresponds to nominal center; 28 December 2021 Hilum Status February 2016 6

Analysis of EMEC Signal: J. Rutherfoord EMEC (LAr gap of 2 mm) expected EMEC 28 December 2021 Hilum Status February 2016 7

Analysis of FCal 250 Signal: A. Savin FCal (LAr gap of 0. 269 mm) Tint=2 ms; Colors indicate different beam impact positions; black corresponds to nominal center; 28 December 2021 Hilum Status February 2016 8

Analysis of FCal 100 Signal: A. Savin FCal (LAr gap of 0. 119 mm) Tint=2 ms; Colors indicate different beam impact positions; black corresponds to nominal center; 28 December 2021 Hilum Status February 2016 9

Analysis of HEC Signal: A. Savin HEC (LAr gap of 1. 97 mm) Tint=20 ms; Colors indicate different beam impact positions; black corresponds to nominal center; 28 December 2021 Hilum Status February 2016 10

From Hilum to ATLAS EMEC HV currents and signal confirm the model expectations; trusting the model, we expect for FCal(270) something like Ic = 8 x 109 p/s; We are not yet ready to fit the Ic knee from the signal dependence on prehistory intensity; but: results indicate that the FCal(270) signal is OK up to 1 x 1010 p/s ! We assume for the FCal at present Ic = 8 -10 x 109 p/s; In the hottest region FCal will be operated at HL-LHC at 80 V rather than 250 V (HV drop at 20 MΩ resistor); this will reduce the critical intensity to Ic= 0. 8 -1. 0 x 109 p/s; The HL-LHC prediction for a luminosity of 7. 5 x 1034 is I = 5 x 109 p/s for the hottest region; At r=5 signal amplitude is reduced by 33% (and Q by 55%) - in addition to due to the HV drop by up to 39% ; FCal(270) is affected in region η > 4. 1 (Andrej’s MC); Main advantage of LAr – stability of calibration – is gone (at high η ): dependence on luminosity; my best guess: jet acceptance will be reduced from η 4. 5 to η 4. 0; 28 December 2021 Hilum Status February 2016 11

Hilum s. FCal (HL-LHC option) with gaps of 119 µm and present FCal (269 µm) NIM A 669 (2012) 47 FCal option for HL-LHC FCal (119 µm) Present FCal (269 µm) 28 December 2021 Hilum Status February 2016 12

Hilum old results: EMEC and HEC NIM A 669 (2012) 47 EMEC HEC 28 December 2021 Hilum Status February 2016 13

IHEP U 70 accelerator and beamline #23: 50 Gev Protons Bunch: width 30 ns at 5%, about 15 ns FWHM; bunch spacing Δt=165 ns; IHEP U 70 accelerator runs specially in ‘debunching off mode‘, i. e. rf bunch structure is fully preserved! Accelerator runs specially only with 5 or less filled bunches per turn (out of 30), i. e. at least 1 μs between single (filled) bunches! Beam extraction via channeling in bent crystal technique ￫ unique opportunity to cover range of intensities required from 106 – 1012 pps; but single bunch intensity measurement required!!! 28 December 2021 Hilum Status February 2016 14