BRANs Sune Jakobsen (BE-BI-PM) LHC BI 2015 summary

The BRAN detector principal The Beam RAte of Neutrals, BRAN, monitors the collision rate in the LHC interactions points by converting neutral particles into hadronic showers. LHC BI 2015 summary BRANsSune Jakobsen 2/19 Principal IP1 IP5 IP8 IP2 Outlook

BRANs at IP1 LHC BI 2015 summary BRANsSune Jakobsen 3/19 Principal IP1 IP5 IP8 IP2 Outlook

The BRAN A at IP1 - hardware No changes done to the detectors in LS1, but new PLC installed to monitor and cotrol the gas system. The LHCf detectors replaced the copper blocks in front of the BRAN for a few month in 2015, and this hugely changed the signals in the BRANs. In TS3 the copper blocks where replaced with the ATLAS ZDC. LHC BI 2015 summary BRANsSune Jakobsen 4/19 Both detectors where mechanically installed in the TANs in 2014 (LEFT side had to be removed and reinstalled again due to a new bake-out). Principal IP1 IP5 IP8 IP2 Outlook

The BRAN A at IP1 - performance The detectors were commissioned at the start of Run2 to have all channels reacting similarly. For the purpose of finding and optimizing collisions the performance and availability has in general been excellent. For the purpose of absolute luminosity scaling the performance is not good (non-linearity and stability effects) and the values are not used by the experiments. LHC BI 2015 summary BRANsSune Jakobsen 5/19 The absolute luminosity scale where adjusted to corresponds to ATLAS. Rescaling was needed a few times during the year. The luminosity per bunch is partly effect at 25 ns by leakages from the bunch before (but neither the operation team or the experiments seems to use this information anyway). For special very low luminosity fills (like the β* = 90 m) a special ”counting mode” was successfully used to make the BRANs more sensitive and help finding first collisions with only probes. One detector started to make discharges and the high voltage had to be lowered. This effected to the per bunch luminosity measurement, but much less the normal use case of finding and optimizing collisions. Principal IP1 IP5 IP8 IP2 Outlook

BRANs at IP5 LHC BI 2015 summary BRANsSune Jakobsen 6/19 Principal IP1 IP5 IP8 IP2 Outlook

The BRAN A at IP5 - hardware No changes done to the detectors in LS1, but new PLC installed to monitor and control the gas system. In TS3 the copper blocks where replaced with the CMS ZDC. LHC BI 2015 summary BRANsSune Jakobsen 7/19 Both detectors where mechanically installed in the TANs in 2014 using the new crane made by CMS. Principal IP1 IP5 IP8 IP2 Outlook

The BRAN A at IP5 - performance The detectors were commissioned at the start of Run2 to have all channels reacting similarly. For the purpose of finding and optimizing collisions the performance and availability has in general been excellent. For the purpose of absolute luminosity scaling the performance is not good (non-linearity and stability effects) and the values are not used by the experiments. LHC BI 2015 summary BRANsSune Jakobsen 8/19 The absolute luminosity scale where adjusted to corresponds to CMS. Rescaling was needed a few times during the year. The luminosity per bunch is partly effect at 25 ns by leakages from the bunch before (but neither the operation team or the experiments seems to use this information anyway). For special very low luminosity fills (like the β* = 90 m) a special ”counting mode” was successfully used to make the BRANs more sensitive and help finding first collisions with only probes. Principal IP1 IP5 IP8 IP2 Outlook

BRANs at IP8 LHC BI 2015 summary BRANsSune Jakobsen 9/19 Principal IP1 IP5 IP8 IP2 Outlook

The BRAN C at IP8 Each of the two detectors are based on 16 quartz rods with a diameter of 10 mm. Each quartz ROD is linked to a UV sensitive photon counting PMT (Hamamatsu P3878P). LHC BI 2015 summary BRANsSune Jakobsen 10/19 The BRAN B (CdTe detector) in IP8 died due to radiation during Run1. A replacement have been made based on Cherenkov light in quartz rods – BRAN C The PMTs and quartz rods are pushed together by springs. Between the PMT and the quartz rod there is the option to put a optical filter. Between the quartz rod, the filter and the PMT optical grease is used. A UV mirror- foil (developed for NA62) are used in the none-PMT end of the rods to maximize light yield. The readout is reused from the old detector and is a simple threshold for each PMT. Principal IP1 IP5 IP8 IP2 Outlook

The PMTs and quartz rods are pushed together by springs. Between the PMT and the quartz rod there is the option to put a optical filter. LHC BI 2015 summary BRANsSune Jakobsen 10/19 Between the quartz rod, the filter and the PMT optical grease is used. A UV mirror-foil (developed for NA62) are used in the none-PMT end of the rods to maximize light yield. The BRAN C at IP8 The readout is reused from the old detector and is a simple threshold for each PMT. 9.6 cm 10.9 cm 65.2 cm Each of the two detectors are based on 16 quartz rods with a diameter of 10 mm. Each quartz ROD is linked to a UV sensitive photon counting PMT (Hamamatsu P3878P). The BRAN B (CdTe detector) in IP8 died due to radiation during Run1 of the LHC. A replacement have been made based on Cherenkov light in quartz rods – BRAN C Principal IP1 IP5 IP8 IP2 Outlook

The BRAN C for IP8 – production and assembly The mechanics were produced mainly in the CERN main workshop. The quartz rods were cleaned like glass for UV mirrors (PH-DT thin film and glass workshop). LHC BI 2015 summary BRANsSune Jakobsen 11/19 The rods are supported inside stainless steel pipes and only touching maximum 4 points in each end. PMTs installed inside mu-metal to insure protection from (weak) magnetic fields. Filters supported directly on the mu-metal. Principal IP1 IP5 IP8 IP2 Outlook

The BRAN C for IP8 – laboratory optimization The quantum efficiency of all PMTs where measured vs wavelength and PMTs with similar performance where grouped. The gain of each PMT was measured vs high voltage and the results parametrized to make HV calculated for equal gain of all PMTs in a group. LHC BI 2015 summary BRANsSune Jakobsen 12/19 The assembled detectors were also tested with internal LED light and cosmic particles. Monochromator Xeon lamp PMT Reference pin-diode PMT LED 1 photoelectron signal Final BRAN C detector Principal IP1 IP5 IP8 IP2 Outlook

The BRAN C for IP8 – Characterization at test beam The detector was characterized at a test beam in H8 LHC BI 2015 summary BRANsSune Jakobsen 13/19 Final readout Absorber BRAN C Light yield measurement of rods. Optimization of filters choice. Investigation of use of optical grease. Threshold of discriminator optimization. Investigation of effect of tilt relative to beam. Investigation of light yield vs absorber thickness. Investigation of use of mirror in the none-PMT end of the rods. Test of full detector with final readout system. Beam Principal IP1 IP5 IP8 IP2 Outlook

The BRAN C for IP8 – Installation before first beam The detector installation was manual (no need for crane like in IP1/5). LHC BI 2015 summary BRANsSune Jakobsen 14/19 New multiwire high voltage cabled installed (several problems with wrongly installed connectors) + additional signal cables. Existing readout upgraded and expanded to the double number of channels. Existing rack, crates, signals cables, copper block etc. re-used. New multichannel high voltage module installed. Principal IP1 IP5 IP8 IP2 Outlook

The BRAN C for IP8 – Performance Already the initial performance of the detector was very good. LHC BI 2015 summary BRANsSune Jakobsen 15/19 In normal operation only the low intensity part is used. The performance for finding and optimizing collisions is excellent and the high sensitive makes it possible to observe a signal with larger separation of the beams (so more likely to find the collisions with fewer scans). Each detector is in reality used as a high and low sensitivity detector with 8 channels each. The absolute scale was adjusted to the LHCb value and the scaling seems reasonable. The stability during a run is very good. The relative bunch luminosity is rather good, but have not been fully explored yet. First 6.5 TeV collisions measured with BRAN C Principal IP1 IP5 IP8 IP2 Outlook

BRANs at IP2 LHC BI 2015 summary BRANsSune Jakobsen 16/19 Principal IP1 IP5 IP8 IP2 Outlook

The BRANs at IP2 The original BRAN B detectors were still working and were therefore reinstalled end of LS1 (only removed for bake-out). LHC BI 2015 summary BRANsSune Jakobsen 17/19 Due to the lower range needed at IP2 it was decided to make a 8 channel version. To minimize work and the number of different spares the design from IP8 was kept (with minor changes for better light tightness), but only 8 rods + 8 PMTs installed. Due to the convincing test beam results for the new BRAN C it was decided to replaced the BRAN Bs with BRAN Cs The BRAN Cs where installed in TS1 (together with Discovery Channel). The signal at IP2 was underestimated, so in TS2 filters was added. After TS2 the performance is very similar to IP8. BRAN B BRAN C Principal IP1 IP5 IP8 IP2 Outlook

Outlook LHC BI 2015 summary BRANsSune Jakobsen 18/19 Principal IP1 IP5 IP8 IP2 Outlook

Outlook Complete spares for BRAN C. LHC BI 2015 summary BRANsSune Jakobsen 19/19 In collaboration with Heraeus Quarzglas (Germany) and WISAG (Switzerland) produce a simplified BRAN C detector (IP1 prototype) to be installed at IP1. Main goal1: Test the radiation hardness of the quartz used at IP2 and IP8 in real conditions to conclude on detectors life time (especially important for IP8 for HL-LHC). In YETS replace one copper block at IP with modified version added space for a new prototype. (The ZDC communities are extremely interested in these test as they also will be valid for ZDC upgrades). New BRAN design for IP1/5 for HL-LHC. New (hopefully only mechanical) design for IP8 for implementation of the BRAN into the TAXN to be installed in LS2. Main goal2: Test 4 additional samples to determined the most radiation hard type of quartz in real conditions and judge if quartz could be an optioning for the upgrade of the BRAN IP1/IP5. Possible new electronics for BRAN C to measure the charge. New luminosity algorithms for existing BRAN C readout (number of rods hit) (already implemented in hardware, but FESA update needed. Will be included in the change to FESA3). Principal IP1 IP5 IP8 IP2 Outlook