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O sistema LASER em estudos de estabilidade e de linearidade dos fotomultiplicadores do TileCal em ATLAS Bruno Galhardo Thursday, April 19, 12  Outline • LHC, ATLAS, TileCal • Sistemas de Calibração • Sistema LASER • Estabilidade • Linearidade • Conclusões Thursday, April 19, 12  LHC Thursday, April 19, 12  ATLAS Thursday, April 19, 12      TileCal TileCal MODULES cell     9:     $%& ' ( )*+,-+./"0-1+⊕0* 2 34!, ( )*+,-+.5""0-1+⊕5"0* 2 645,  Mede a radiação produzida por partículas carregadas nos cintiladores plásticos PMT WLS fiber 1.60 m Tile 11 Tile rows Calor 2004 – Perugia 1 April, Calibration Session 3 5.64 m Módulo do TileCal Thursday, April 19, 12 ? Fran (0.1 x ATL  Sistemas de calibração • O objectivo da calibração é minimizar a diferença entre a energia da partícula e a energia reconstruída pelo detector • Diferentes sistemas monitorizam e calibram diferentes partes do TileCal Thursday, April 19, 12  Sistema LASER • Pulsos do LASER produzem uma resposta nos PMTs semelhante aos sinais produzidos por partículas, com a vantagem que, no caso do LASER conhecemos com precisão a energia inicial • A monitorizaçao do sistema é importante uma vez que a resolução de energia vai depender bastante da nossa compreenção da resposta dos PMT • Principal objectivo: medir a estabilidade e linearidade dos 9852 PMTS usados no detector Thursday, April 19, 12  in2p LASER box • LASER - capaz de iluminar os 9852 PMTs do TileCal • Espelho semi reflector - divide a luz entre o PD1/PMTs e o TileCal • 4 fotodiodos - possibilitam medida independente do sinal do LASER • 2 PMTs - usados no trigger dos eventos de LASER • Roda com 8 filtros - cada filtro com 1 atenuação, que possibilitam cobrir todo o intervalo de energias do TileCal [100MeV - 1.5TeV] Thursday, April 19, 12  ed in Section 2, and some first results ned during TileCal commissioning are Conclusions are given in Section 4. and linearity. However, illuminating simultaneously 9 powerful light source. Pulse shape requi width) has driven our choice toward a co DPSS (Diode-Pumped Solid State) LAS SPECTRA-PHYSICS [4]. This is a frequ 1º Splitter - localizado LASER emitting a 532nm perto greenda light be box, feixe em 384 theLaser first part ofdivide a setupodescribed on Fig. 1 fibras que vão para os módulos distinct parts: the LASER box and the lig do TileCal (3 fibras vão para 3 fotodíodos da LASER box) LASER box is the main component provides its absolute calibration and trig of theMarço light 2011 emitted by the LASER hea there and sent to one photodiode and tw the TileCal PMTs). The photodiode is calibration of the system, and the PMTs the LASER events. In order to monitor li levels, three other diodes are collecting Splitter - divide luz para first2ºbeam splitter. Theafour photodiodes um dos PMTs intocada the same thermally-regulated box, ar using an 241 Am radioactive source. T Distribuição de luz from the to the TileCal channels Thursday, AprilLASER 19, 12 Number of Events • Mean 167.3 RMS 32.41 Underflow 0 Overflow 0 35 30 25 20 15 10 5 0 0 • 50 100 150 200 250 300 mean fiber signal  outgoing light in order to cover the whole TileCal dynamic (from 100 MeV/PMT to 1.5 TeV/PMT). Runs de LASER • Semanalmente são efectuadas runs de LASER para monitorização dos PMTs, para ganho alto (filtro 8) e baixo (filtro 6). 2.2. Electronics and software aspects is monitored, controlled, Adicionalmente, durante runs The desystem física, impulsos de and if necessary interlocked, by a set of 6 electronic cards located in a VME crate LASER são enviados nos gapssituated das right partículas para below the LASER box.verificar This is also where the timing of the LASER pulses is handled. Indeed, LASER event o estado das PMTs durante a aquisição de dados are taken within ATLAS normal physics run, during the 3 µs Number of Events Entries 10005 Mean 92.23 RMS 2.886 350 300 250 200 150 100 50 0 80 Thursday, April 19, 12 85 90 95 100 105 Signal (in pC) in2p3-00461504, version 1 - 4 Mar 2010 • Then, the light outgoing the LASER box is brought via a 1m long liquid fiber towards a first beam-splitter. This splitter dispatches the primary beam toward a bunch of ⇠400 clear fibres. In order to improve the splitting uniformity, the amount of light going out of the secondary fibres is tunable via dedicated connectors. Long clear fibers then bring the light from the counting rooms (where the main system stands) to TileCal modules. The light finally enters the modules where it is split a last time before reaching the PMTs. th wa on ar cu to gap occurring at the end of each LHC cycle. The timeline of a LASER calibration pulse is sketched on Fig. 2. Fig PM It in th pr 4.  Monitorização e Calibração mic 1m tter lear unt ediom Cal it a • Estabilidade - A resposta do PMT tem de ser constante no tempo Figure 3: How linearity and stability are tested with the LASER system ? • then), have shown that PMTs relative stability over 100 days Linearidade - A resposta de um was better than 1% for most of the channels. Analyses are still tem detests aumentar linearmente ongoing in order to improve those results.PMT The linearity are more sensitive to the system intrinsic stability, and we are com a energia currently working on possible technical improvements in order to fulfill the necessary requirements for those tests. terrate ythe and stability are tested with the LASER system ? Thursday, April 19, 12  StabilityEstabilidade using the laser runs 5 Low Gain • High Gain Relative Variação variation using the latest run (17/03/2011) 0,10% / 0,12% / HG) relativa numa run de 22/03/2011, para (LG todas as This is the relativedesde variation run taken in feb. 23rd PMTs a w.r.t. run the anterior. Thursday, April 19, 12  100 LASER in Phys runs LASER Calib f6 LASER Calib f8 Estabilidade com o tempo 0 24/02 26/03 25/04 25/05 24/06 24/07 23/08 22/09 22/10 Time (day/month) PMT Signal normalized Figure 6: Comparison of the signal from photodiode 1 in the LASER box from physics runs and LASER calibration runs. 1.03 LBA1 PMT1 1.02 1.01 1 0.99 0.98 0.97 • • • Thursday, April 19, 12 LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 26/03 25/04 25/05 24/06 24/07 23/08 22/09 22/10 Time (day/month) Figure 7: Comparison the fourentre samples, each one normalized to the their first2010 point value, for Estabilidade debetween 1 PMT Março e Outubro one TileCal PMT (PMT1 in LBA1): in black the values from the physics runs, in red and green from the LASER calibration runs using filter 6 and 8 respectively and in blue the Cesium runs. The PMT response on the LASER runs with filter 8 (6) was normalized to the LASER box photodiode 2 (4) signal. Resultados normalizados aos fotodíodos Variações menores que 1%  PMT Signal normalized PMT Signal normalized 1.05 1 0.95 0.9 1 0.95 0.9 Correlação entre runs 0.85 0.85 0.8 LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 0.75 0.7 0.65 DRAFT November 15, 2010 – 18 : 29 26/03 25/04 25/05 0.8 0.75 24/06 1124/07 23/08 22/09 22/10 Time (day/month) LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 26/03 25/04 25/05 0.9 0.85 0.95 1 0.99 0.9 0.98 LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 0.85 0.8 0.97 LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 0.75 0.7 0.65 26/03 25/04 25/05 LASER in Phys runs LASER Calib f6 0.96 LASER Calib f8 Cesium runs 0.8 0.75 24/06 24/07 23/08 22/09 22/10 Time (day/month) 26/03 25/04 25/05 24/06 0.99 0.98 0.97 0.96 LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 26/03 25/04 25/05 1.02 1 0.98 (a) 0.9 0.75 0.9 24/07 0.88 0.7 LASER in Phys runs LASER Calib f6 23/08 LASER 22/09 Calib 22/10f8 Time (day/month) Cesium runs 26/03 25/04 25/05 0.65 (c) 24/07 0.85 0.8 0.94 0.75 0.9 24/07 0.88 0.7 LASER in Phys runs LASER Calib f6 23/08 LASER 22/09 Calib 22/10 f8 Time (day/month) Cesium runs 26/03 25/04 25/05 0.65 LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 26/03 24/06 24/07 25/04 25/05 23/08 22/09 22/10 Time (day/month) 24/06 24/07 (b) 1.02 1 0.94 0.92 0.9 0.88 LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 26/03 24/06 0.9 (c) 0.85 0.94 0.95 0.96 0.92 24/06 23/08 22/09 22/10 Time (day/month) 0.98 1 Figure 12: Examples of some 0.98 PMTs with unstable behavior but with good corr LASER and the Cesium runs:0.96a) EBC42 - PMT29, b) EBC53 - PMT43 and c) LBC1 0.95 0.8 (a) • 1 0.96 0.92 24/06 25/05 1 PMT Signal normalized 1 PMT Signal normalized 1.01 24/07 25/04 1.02 (b) PMT Signal normalized PMT Signal normalized (a) 26/03 PMT Signal normalized 0.95 1 1.01 24/07 (b) PMT Signal normalized 1 PMT Signal normalized 1.05 PMT Signal normalized PMT Signal normalized (a) 24/06 25/04 25/05 23/08 22/09 22/10 Time (day/month) 24/06 (b) 0.86 0.84 0.82 24/07 23/08 22/09 22/10 Time (day/month) LASER in Phys runs LASER Calib f6 LASER Calib f8 Cesium runs 26/03 25/04 25/05 24/06 24/07 23/08 22/09 22/10 Time (day/month) (c) PMT Signal normalized Figure 13: Examples of some PMTs with unstable behavior and with disagreement Informação das diferentes runs são úteis para perceber a and the Cesium runs: a) LBA17 PMT1, b) LBC22 PMT8 and c) EBA43 - PMT3 Figure 12: Examples of some PMTs with unstable behavior but with good correlation between the LASER and the Cesium runs: a) EBC42 b) EBC53 -de PMT43 and c) LBC12 - PMT18. origem do- PMT29, problema um determinado PMT 1.02 1 0.98 0.96 0.94 0.92 0.9 0.88 Thursday, April 19, 12 0.86 LASER in Phys runs LASER Calib f6  Comparação com o Cesium Three cases 4 !  Different cases have to be treated : Period 09/2009 # 02/2010 Case 1 : Small variations Case 2 : Significant variations Seen by Las and Cs Case 3 : Disagreement between Las and Cs • Thursday, April 19, 12 Com algumas excepções, para variações maiores que 3%, quando o LASER mede uma grande variação o Cesium mede a mesma variação  Linearidade • • • Runs para 7 filtros diferentes • Intervalo do fotodíodo 4 ajustado para cada filtro de forma a conter os sinais de 14k a 30k • • Fit linear (2 parâmetros) para cada filtro y = a.(x - b/a) Com 6 intensidades de LASER: 14k, 18k, 22k, 26k, 28k and 30k Não se consideram sinais maiores que 700GeV onde se começa a verificar não linearidade fit − PMT Residual = fit Resíduos calculados para cada ponto PMT_000 F1 PMT signal/PD signal y = ax 0.3 0.29 0.28 0.27 PMT signal (in GeV) PMT_000 F6 -3 ×10 120 100 y = a(x - b/a) 80 0.26 60 0.25 40 0.24 0.23 20 0.22 Fit example Thursday, April 19, 12 200 400 600 800 1000 1200 1400 1600 1800 PD4 signal (in ADC) 0 200 400 600 800 1000 1200 1400 1600 1800 PD4 signal (in ADC)  Offsets (b/a) 300 Entries Mean RMS Underflow Overflow F1 9609 60.71 13.76 40 297 600 F2 500 250 200 400 150 300 100 200 50 100 Entries Mean RMS Underflow Overflow 9603 57.32 6.843 9 420 180 160 Entries Mean RMS Underflow Overflow F3 9598 58.61 21.21 318 864 140 120 100 80 60 40 0 0 10 20 30 40 50 60 70 80 300 F4 0 0 100 Entries Mean RMS Underflow Overflow 400 350 90 20 9543 55.5 10.81 11 155 300 10 20 30 40 50 60 70 80 100 Entries 8241 Mean 74.27 RMS 10.33 Underflow 2 Overflow 24 F5 250 90 0 10 20 30 40 50 60 70 80 350 100 Entries Mean RMS Underflow Overflow 450 400 90 F6 300 250 200 250 200 150 200 150 150 100 100 100 50 50 0 0 10 20 30 40 50 60 70 80 F8 250 200 150 100 50 0 0 10 20 Thursday, April 19, 12 30 40 50 60 70 80 90 0 0 100 Entries Mean RMS Underflow Overflow 350 300 90 100 50 9609 62.66 10.73 20 57 10 • • • 20 30 40 50 60 70 80 90 100 0 0 10 20 30 40 50 60 70 Offset atribuido ao PD4 Valor médio ~60 para todos os filtros Parâmetros variam bastante 80 90 100 9592 67.17 7.91 7 18  Resultados • Plot com o resíduo médio em cada ponto vs o sinal médio de todas as PMTs do TileCal para cada combinação filtro/intensidade • Os erros são a RMS dos histogramas Filter 1 Filter 2 2 Filter 3 Filter 4 1.5 Filter 5 Filter 6 Filter 8 1 0.5 without 14k Residuals (in %) Residuals (in %) with 14k Filter 4 0.5 -1 -1 -1.5 -1.5 10 2 10 Mean PMT Signal (in GeV) Filter 8 1 -0.5 1 Filter 5 Filter 6 -0.5 -1 Filter 3 1.5 0 10 Filter 2 2 0 -2 Filter 1 -2 -1 10 1 10 2 10 Mean PMT Signal (in GeV) • Removendo o ponto relativo à intensidade de LASER mais baixa, 14k, de cada filtro os resultados centram-se no zero e com variações menores que 0.5% • Filtro 3 com RMS maior porque o intervalo de energias se encontra na transição entre ganho alto e baixo Thursday, April 19, 12  Fit com todos os filtros • • • Aplicando a correção f em cada fit por filtro y = a.f.(x - b’) f para cada filtro é normalizado ao f5 para cancelar erros sistemáticos O valor do PD é corrigido com o valor médio b’ tirado dos fits individuais Residuals (in %) without 14k Graph Graph 700 400 600 350 300 500 250 400 200 300 Filter 1 Filter 2 3 Filter 3 Filter 4 Filter 5 2 Filter 6 Filter 8 1 0 150 200 100 0 0 -1 100 50 200 400 600 Fit example 800 1000 1200 1400 1600 1800 0 0 200 400 Bad fit example 600 800 1000 1200 1400 -2 -3 -1 10 1 • • Parâmetro f tem elevada precisão, baixo RMS • Não é uma boa maneira de identificar as “más” PMTs. 10 Maior fonte de erros vem de b’. O qual tem grande impacto para alguns PMTs Thursday, April 19, 12 2 10 Mean PMT Signal (in GeV)  PMT aleatória do TileCal como referência Residuals (in %) Filter 2 Filter 3 6 Filter 4 Filter 5 Filter 6 4 Filter 8 2 Filter 1 Filter 2 Filter 3 6 Filter 4 Filter 5 Filter 6 4 Filter 8 2 EBC32_5 as reference Filter 3 6 -2 -2 -4 -4 -4 -6 -6 -6 2 -1 10 Mean PMT Signal (in GeV) PD4 as reference 10 1 10 2 10 Mean PMT Signal (in GeV) Filter 8 2 -2 10 Filter 6 4 0 1 Filter 4 Filter 5 0 -1 Filter 1 Filter 2 0 10 Residuals (in %) EBA23_3 as reference Residuals (in %) Filter 1 Residuals (in %) LBA12_1 as reference -1 10 1 10 Filter 1 Filter 2 Filter 3 6 Filter 4 Filter 5 Filter 6 4 Filter 8 2 0 -2 -4 -6 -1 10 1 Thursday, April 19, 12 10 2 10 Mean PMT Signal (in GeV) • • Fit de 1 parâmetro y = ax Usando todas as intensidades 2 10 Mean PMT Signal (in GeV)  PMT da mesma fibra como referência Residuals (in %) PMT from the same fiber as reference Filter 1 Filter 2 3 Filter 3 Filter 4 Filter 5 2 Filter 6 Filter 8 1 • • Fit y = ax • Resíduos menores que 1% 0 -1 -2 -3 -1 10 Thursday, April 19, 12 1 10 2 10 Mean PMT Signal (in GeV) Comparando 2 PMTs da mesma fibra (depois do 2o splitter) as variações médias desaparecem  Comparação dos 3 PD Residuals (in %) PD3 - Filter 6 10 PD2 - Filter 8 8 PD4 - Filter 6 6 PD4 - Filter 8 4 2 0 -2 -4 -6 -8 -10 • Thursday, April 19, 12 -1 10 1 10 2 10 Mean PMT Signal (in GeV) Há um bom acordo entre os resultados usando o PD2 e PD3 e o PD4  PD1 e PMT1 Filter 1 10 Filter 2 8 Filter 4 6 Filter 6 Filter 3 Filter 5 Filter 8 4 8 Filter 4 6 Filter 6 0 -2 -2 -4 -4 -10 -1 10 Filter 3 Filter 5 Filter 8 4 0 -8 PMT 1 -6 -8 1 10 with 14k Residuals (in %) Filter 2 2 PD1 2 10 Mean PMT Signal (in GeV) Filter 1 10 2 -6 -10 -1 10 1 10 2 10 Mean PMT Signal (in GeV) Filter 1 10 Filter 2 8 Filter 4 6 Filter 6 Filter 3 Filter 5 Filter 8 4 2 0 -2 -4 -6 PD1 -8 -10 without 14k Residuals (in %) Residuals (in %) without 14k -1 10 Thursday, April 19, 12 1 10 2 10 Mean PMT Signal (in GeV) • • Grandes variações nos resíduos Referência após o 1o splitter necessária para cancelar os erros introduzidos pelo sistema  Conclusões Thursday, April 19, 12 • Resultados da estabilidade mostram variações médias menores que 1% • PMTs com maus comportamentos facilmente identificáveis pelo sistema • Para a linearidade ainda não há um bom método para determinar linearidade em todo o intervalo de energias. • Confirmam-se alguns erros sistemáticos introduzidos pelo sistema óptico ao longo do sistema