Photodit
® (porfimer sodium) is a complex mixture of porphyrin-modified oligomers that has demonstrated high photoactivity during photodynamic therapy of malignant tumors. Hematoporphyrin derivative ...monomer precursors of Photodit
® and its oligomers were analyzed using liquid chromatography and mass spectrometry to determine their chemical composition and structures. Hematoporphyrin (
M-3),
O,
O′-diacetylhematoporphyrin (
M-6), and isomers of 8(-3)-hydroxyethyl-3(-8)-vinyldeuteroporphyrin (
M-2), 8(-3)-(1-acetoxyethyl)-3(-8)-vinyldeuteroporphyrin (
M-4), and
O-acetylhematoporphyrin (
M-5), in ratio 0.59:0.94:0.21:0.34:1.00, were identified as hematoporphyrin derivative monomer precursors. The main compounds of Photodit
® as a porfimer sodium salt were dimers:
D-1 {di-8(-3)-hydroxyethyl-3(-8)-vinyldeuteroporphyrin ether},
D-2 {Hematoporphyrin-8(-3)-hydroxyethyl-3(-8)-vinyldeutroporphyrin ether}, and
D-3 {Dihematoporphyrin ether} in ratio 0.51:1.00:0.50, and trimers:
T-1 {(M-2)–(D-2) ether},
T-2 {(D-2)–(M-3) ether}, and
T-3 {(D-3)–(M-3) ether} in ratio 0.98:1.00:0.44, respectively. An average oligomer length of 2.23 porphyrin units was determined.
The CMS muon system includes in both the barrel and endcap region Resistive Plate Chambers (RPC). They mainly serve as trigger detectors and also improve the reconstruction of muon parameters. Over ...the years, the instantaneous luminosity of the Large Hadron Collider gradually increases. During the LHC Phase 1 ( similar to first 10 years of operation) an ultimate luminosity is expected above its design value of 10 super(34) cm super(-2)s super(-1) at 14 TeV. To prepare the machine and also the experiments for this, two long shutdown periods are scheduled for 2013-2014 and 2018-2019. The CMS Collaboration is planning several detector upgrades during these long shutdowns. In particular, the muon detection system should be able to maintain a low-pT threshold for an efficient Level-1 Muon Trigger at high particle rates. One of the measures to ensure this, is to extend the present RPC system with the addition of a 4th layer in both endcap regions. During the first long shutdown, these two new stations will be equipped in the region degree ' eta degree ' < 1.6 with 144 High Pressure Laminate (HPL) double-layer RPCs operating in avalanche mode, with a similar design as the existing CMS endcap chambers. Here, we present the upgrade plans for the CMS RPC system for the fist long shutdown, including trigger simulation studies for the extended system, and details on the new HPL production, the chamber assembly and the quality control procedures.
The Resistive Plate Chambers (RPCs) are employed in the CMS experiment at the LHC as dedicated trigger system both in the barrel and in the endcap. This note presents results of the RPC detector ...uniformity and stability during the 2011 data taking period, and preliminary results obtained with 2012 data. The detector uniformity has been ensured with a dedicated High Voltage scan with LHC collisions, in order to determine the optimal operating working voltage of each individual RPC chamber installed in CMS. Emphasis is given on the procedures and results of the High Voltage calibration. Moreover, an increased detector stability has been obtained by automatically taking into account temperature and atmospheric pressure variations in the CMS cavern.
The Gas GainMonitoring (GGM) system of the Resistive Plate Chamber (RPC) muondetector in the Compact Muon Solenoid (CMS) experiment provides fast and accurate determinationof the stability in the ...working point conditions due to gas mixture changes in the closed looprecirculation system. In 2011 the GGM began to operate using a feedback algorithm to control theapplied voltage, in order to keep the GGM response insensitive to environmental temperature andatmospheric pressure variations. Recent results are presented on the feedback method used and onalternative algorithms.
Resistive Plate Chambers have been chosen as dedicated trigger muon detector for the Compact Muon Solenoid experiment 1 at the Large Hadron Collider 2 at CERN. The system consists of about 3000m ...super(2) of double gap RPC chambers placed in both the barrel and endcap muon regions. About 5.6 fb super(-1) (2010-2011) of proton-proton collision data have been used to study the performance of the RPC detector and trigger. A full high voltage scan of all the RPC chambers has been done at beginning of 2011 data taking to evaluate the working point chamber by chamber and to eventually spot aging effects. The excellent behaviour of the RPC detector can be summarized with an average detector efficiency of about 97%, an average cluster size of 1.8 and an intrinsic noise rate of 0.1 Hz/cm super(2). This is a clear fulfilment of all the requirements decided 18 years ago in the CMS TDR document 3.
The CMS experiment will install a RE4 layer of 144 new Resistive Plate Chambers (RPCs) on the existing york YE3 at both endcap regions to trigger high momentum muons from the proton-proton ...interaction. In this paper, we present the detailed procedures used in the production of new RPC gas gaps adopted in the CMS upgrade. Quality assurance is enforced as ways to maintain the same quality of RPC gas gaps as the existing 432 endcap RPC chambers that have been operational since the beginning of the LHC operation.
In this paper, we report a systematic study of multigap Resistive Plate Chambers (RPCs) for high- eta triggers in CMS. Prototype RPC modules with four- and six-gap structures have been constructed ...with phenolic high-pressure-laminated (HPL) plates and tested with cosmic muons and gamma rays irradiated from a 200-mCi super(137)Cs source. The detector characteristics of the prototype multigap RPCs were compared with those of the double-gap RPCs currently used in the CMS experiment at LHC. The mean values for detector charges of cosmic-muon signals drawn in the four- and six-gap RPCs for the efficiency values in the middle of the plateau were about 1.5 and 0.9 pC, respectively, when digitized with charge thresholds of 150 and 100 fC, respectively. They were respectively about one third and one fifth of that drawn in the current CMS doublegap RPC with a charge threshold of 200 fC. We concluded from the current R&D that use of the current phenolic-HPL multigap RPCs is advantageous to the high- eta triggers in CMS in virtue of the smaller detector pulses.
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